diff --git a/frontend/README-tcltk b/frontend/README-tcltk
index 2b499d96..87e2b9d3 100644
--- a/frontend/README-tcltk
+++ b/frontend/README-tcltk
@@ -8,6 +8,12 @@ Provided under GNU GPL version 2 or later.
 xorriso-tcltk is mainly a proof of concept for a frontend that operates
 xorriso in dialog mode.
 
+Dependencies:
+- xorriso ISO 9660 Rock Ridge filesystem manipulator and CD/DVD/BD burn program
+- Tcl programming language
+- Tk widget toolkit
+- optionally the Tcl/Tk package BWidget
+
 It exercises several fundamental gestures of communication:
 - connecting via two pipes
 - sending commands
@@ -47,6 +53,9 @@ in order to get the particular help text for that element.
 There is no need to close the help window. Just click another element to
 get another help text.
 
+The "Help" button in the upper right corner gives a short overview and
+instructions for several common use cases.
+
 
                          Program start options
 
@@ -55,7 +64,7 @@ So here is the output of  xorriso-tcltk --help :
 ------------------------------------------------------------------------
 
 Usage:
-  frontend/xorriso-tcltk [options]
+  /usr/bin/xorriso-tcltk [options]
 Options:
  All options must be given with two dashes ("--option") in
  order to distinguish them from any options of the Tcl shell.
@@ -76,6 +85,9 @@ Options:
  --silent_start
      Do not issue the start message xorriso-tcltk-version.
      This works only if --silent_start is the first argument.
+ --no_bwidget
+     Do not try to load the Tcl/Tk package BWidget which is
+     a prerequisite for the "/" file browser buttons.
  --geometry {+|-}X{+|-}Y
      Sets the position of the main window.
  --click_to_focus
diff --git a/frontend/xorriso-tcltk b/frontend/xorriso-tcltk
index 595a7960..ef5dc2b3 100755
--- a/frontend/xorriso-tcltk
+++ b/frontend/xorriso-tcltk
@@ -42,6 +42,9 @@ proc print_usage {argv0} {
   puts stderr " --silent_start"
   puts stderr "     Do not issue the start message xorriso-tcltk-version."
   puts stderr "     This works only if --silent_start is the first argument."
+  puts stderr " --no_bwidget"
+  puts stderr "     Do not try to load the Tcl/Tk package BWidget which is"
+  puts stderr "     a prerequisite for the \"/\" file browser buttons."
   puts stderr " --geometry {+|-}X{+|-}Y"
   puts stderr "     Sets the position of the main window."
   puts stderr " --click_to_focus"
@@ -144,11 +147,14 @@ set devlist ""
 # Intermediate storage for messages until the GUI is up with .msglist box
 set pre_msglist ""
 
-# Whether overwriting of files in ISO and on disk is allowed
-set overwrite_files 1
+# Whether overwriting of files in the ISO model is allowed
+set overwrite_iso_files 1
 
-# If overwrite_files is 1 : Wether overwriting of ISO directories is allowed
-set overwrite_dirs 0
+# If overwrite_iso_files is 1: Wether overwriting of ISO directories is allowed
+set overwrite_iso_dirs 0
+
+# Whether overwriting of files on disk is allowed
+set overwrite_disk_files 0
 
 # The file where to log commands and replies for debugging purposes
 set log_file ""
@@ -157,6 +163,9 @@ set log_conn stderr
 # Whether to log all commands and replies to the log_file 
 set logging 0
 
+# The result of the most recent isofs_ls run
+set isofs_ls_result ""
+
 
 # xorriso specific constants
 
@@ -238,10 +247,6 @@ proc await_all_replies {} {
     log_puts "$line"
     if {[string range "$line" 0 0] == "M"} {
        if {[string range "$line" 5 end] == "$mark_count"} {
-
-         # <<<
-         # puts stderr "sync mark"
-
   break
        } else {
          # outdated mark message
@@ -253,16 +258,6 @@ proc await_all_replies {} {
   }
 
   display_busy 0
-
-  # <<< debug
-  # for {set i 0} {$i < $info_count} {incr i} {
-  #   set line [lindex "$info_list" $i]
-  #   puts stderr "info $i : $line"
-  # }
-  # for {set i 0} {$i < $result_count} {incr i} {
-  #   set line [lindex "$result_list" $i]
-  #   puts stderr "result $i : $line"
-  # }
 }
 
 
@@ -294,20 +289,12 @@ proc de_pkt_line {line} {
       lappend result_list  "$emerging_result"
       incr result_count
       display_msg "$emerging_result"
-
-      # <<<
-      # puts stderr "result: $emerging_result"
-
       set emerging_result ""
     } else {
       lappend info_list "$emerging_info"
       incr info_count
       display_msg "$emerging_info"
       scan_info_for_event "$emerging_info"
-
-      # <<<
-      # puts stderr "info: $emerging_info"
-
       set emerging_info ""
     }
   }
@@ -370,10 +357,6 @@ proc de_sieve {} {
   for {set i 2} {$i < [llength "$result_list"]} {incr i} {
     set line ""
     set num_lines [lindex "$result_list" $i]
-
-    # <<<
-    # puts stderr "de_sieve : num_lines = $num_lines"
-
     for {set j 0} {$j < "$num_lines"} {incr j} {
       incr i
       set line "$line[lindex "$result_list" $i]"
@@ -647,8 +630,6 @@ proc set_inquired_dev {} {
 #  help of xorriso.)
 #
 proc inquire_dev {} {
-  global result_list
-
   set disp_en_mem [set_display_msg 0]
   send_marked_cmd "-status -dev"
   handle_result_list set_inquired_dev "''" "''" 2 0
@@ -658,6 +639,45 @@ proc inquire_dev {} {
 }
 
 
+# Parse-by-xorriso handler function for proc isofs_ls
+#
+proc isofs_ls_handler {} {
+  global result_list isofs_ls_result
+
+  if {[lindex "$result_list" 0] == "total"} {return ""}
+  lappend isofs_ls_result \
+       "[string range [lindex "$result_list" 0] 0 0] [lindex "$result_list" 8]"
+}
+
+
+# Produce a list of all files in a directory of the ISO model
+#
+proc isofs_ls {dir} {
+  global isofs_ls_result
+
+  set isofs_ls_result ""
+  set disp_en_mem [set_display_msg 0]
+  send_marked_cmd "-lsl [make_text_shellsafe "$dir"]"
+  handle_result_list isofs_ls_handler "''" "''" 0 0
+  set_display_msg "$disp_en_mem"
+  return "$isofs_ls_result"
+}
+
+
+# Tells the file type of an absolute path in the ISO model.
+# Indicator characters like with ls -l. Empty text means non existing file.
+#
+proc isofs_filetype {path} {
+  global result_list
+
+  set disp_en_mem [set_display_msg 0]
+  send_marked_cmd "-lsdl [make_text_shellsafe "$path"]"
+  set_display_msg "$disp_en_mem"
+  if {[llength "$result_list"] < 1} {return ""} 
+  return [string range [lindex "$result_list" 0] 0 0]
+}
+
+
 # Verify that the connected process runs a xorriso program that is modern
 # enough. This is done before sending xorriso the setup commands.
 #
@@ -729,6 +749,7 @@ proc setup_xorriso {} {
   set cmd "$cmd -osirrox on"
   set cmd "$cmd -iso_rr_pattern off"
   set cmd "$cmd -disk_pattern off"
+  set cmd "$cmd -follow mount:limit=100"
 
   send_marked_cmd "$cmd"
 
@@ -763,10 +784,6 @@ proc start_bulkparse {prefix separators max_words flag num_lines} {
   set bulk_parse_num_texts "$num_lines"
   if {"$bulk_parse_mode" == 1} {
     set cmd "-msg_op parse_bulk \"$prefix $separators $max_words $flag $num_lines\""
-
-    # <<<
-    # puts stderr "start_bulkparse : $cmd"
-
     send_async_cmd "$cmd"
     # Do not wait for mark
   }
@@ -791,10 +808,6 @@ proc submit_bulkparse {text} {
 
   if {"$bulk_parse_mode" == 0} {
     set cmd "-msg_op parse \"$bulk_parse_prefix $bulk_parse_separators $bulk_parse_max_words $bulk_parse_flag $num_lines\""
-
-    # <<<
-    # puts stderr "submit_bulkparse: cmd = $cmd"
-
     send_async_cmd "$cmd"
   } else {
     log_puts ">>>>>  $num_lines"
@@ -804,11 +817,7 @@ proc submit_bulkparse {text} {
   puts $cmd_conn "$text"
   flush $cmd_conn
 
-  # <<<
-  # puts stderr "submit_bulkparse: text sent"
-
   if {"$bulk_parse_mode" != 1} {
-
     set loop_limit 2
     while {"$result_count" < "$loop_limit"} {
       set ret [gets "$reply_conn" line]
@@ -821,14 +830,9 @@ proc submit_bulkparse {text} {
       if {"$result_count" == 2} {
         set num_replies [lindex "$result_list" 1]
         set loop_limit [expr "$num_replies * 2 + 2"]
-
-        # <<<
-        # puts stderr "submit_bulkparse: loop_limit = $loop_limit"
-
       }
     }
     de_sieve
-
   }
   set_display_msg "$disp_en_mem"
 }
@@ -844,16 +848,11 @@ proc read_bulkparse {handler_proc num_texts} {
   if {"$bulk_parse_mode" != 1} { return ""}
 
   set disp_en_mem [set_display_msg 0]
-
-  # <<<
-  # puts stderr "read_bulkparse : handler_proc = $handler_proc , num_texts = $num_texts"
-
   for {set i 0} {"$i" < "$num_texts"} {incr i} {
     clear_reply_lists
     read_parse_reply
     $handler_proc
   }
-
   set_display_msg "$disp_en_mem"
 }
 
@@ -876,10 +875,6 @@ proc read_parse_reply {} {
     if {"$result_count" == 2} {
       set num_replies [lindex "$result_list" 1]
       set loop_limit [expr "$num_replies * 2 + 2"]
-
-      # <<<
-      # puts stderr "submit_bulkparse: loop_limit = $loop_limit"
-
     }
   }
   de_sieve
@@ -891,7 +886,7 @@ proc read_parse_reply {} {
 # This is used to split the result lines of -lsl into words from which
 # handler proc isolist_parse_handler picks the info which it displays
 # in .stbox isolist .
-# Note that iall parameters must be xorriso words. E.g. empty prefix or
+# Note that all parameters must be xorriso words. E.g. empty prefix or
 # separator have to be submitted as tcl string "''" rather than "".
 #
 proc handle_result_list {handler_proc \
@@ -907,16 +902,9 @@ proc handle_result_list {handler_proc \
     set chunk_size "$raw_line_count"
   }
   start_bulkparse "$prefix" "$separators" "$max_words" "$flag" "$chunk_size"
-
-  # <<<
-  # puts stderr "isodir_return : chunk_size = $chunk_size"
-
   set submit_count 0
   set submit_in_chunk_count 0
   foreach i "$raw_list" {
-    # <<<
-    # puts stderr "isodir_return : submit_bulkparse $i"
-
     submit_bulkparse "$i"
     incr submit_count
     incr submit_in_chunk_count
@@ -924,10 +912,6 @@ proc handle_result_list {handler_proc \
       $handler_proc
     }
     if {"$bulk_parse_mode" == 1 && "$submit_in_chunk_count" == "$chunk_size"} {
-
-      # <<<
-      # puts stderr "isodir_return : submit_in_chunk_count = $submit_in_chunk_count"
-
       read_bulkparse "$handler_proc" "$chunk_size"
       set todo [expr "$raw_line_count" - "$submit_count"]
       if {"$todo" <= 0} {
@@ -940,10 +924,6 @@ proc handle_result_list {handler_proc \
       }
       start_bulkparse "$prefix" "$separators" "$max_words" "$flag" \
                       "$chunk_size"
-
-      # <<<
-      # puts stderr "isodir_return : further chunk_size = $chunk_size"
-
       set submit_in_chunk_count 0
     }
   }
@@ -993,7 +973,7 @@ set burn_write_defect_mgt 0
 # Answer of yes/no window
 set answer_of_yesno ""
 
-# The local filesystem address to be mapped into isodir_adr
+# The hard disk filesystem address to be mapped into isodir_adr
 set insert_from_adr ""
 
 # Whether to insert with leafname of insert_from_adr underneath isodir_adr
@@ -1004,7 +984,7 @@ set insert_underneath 1
 # rather than isodir_adr
 set insert_at_selected 0
 
-# The local filesystem address to which to extract from isodir_adr
+# The hard disk filesystem address to which to extract from isodir_adr
 set extract_to_adr ""
 
 # Whether to insert with leafname of insert_from_adr underneath isodir_adr
@@ -1029,6 +1009,26 @@ set ack_window_is_active 0
 set yesno_window_is_active 0
 set help_window_is_active 0
 
+# Whether the help window already has a scroll bar
+set help_window_has_scroll 0
+
+# Whether there is the BWidget package available: 0=unknown, 1=yes, -1=banned
+#
+set have_bwidget 0
+set bwidget_version ""
+
+# Whether the .browse_disk_window is already displayed
+set browse_disk_window_is_active 0
+set browse_disk_window_var ""
+
+# Whether the .browse_iso_window is already displayed
+set browse_iso_window_is_active 0
+set browse_iso_window_var ""
+
+# Whether a selection event in the file browser shal trigger a Return in
+# the associated text field after setting the selected value.
+set browse_select_is_return 1
+
 
 # ------ GUI callback procedures ----
 
@@ -1042,6 +1042,7 @@ proc cmdline_return {} {
   global highest_cmd_sev_msg
 
   reset_highest_cmd_sev
+  set_display_msg 1
   send_marked_cmd "$cmdline"
   set cmdline ""
 
@@ -1243,8 +1244,8 @@ proc scan_for_drives {} {
   update idletasks
 
   # Command -devices drops all aquired drives
-  refresh_indev
   refresh_outdev
+  refresh_indev
 }
 
 
@@ -1365,6 +1366,12 @@ proc isodir_return {caller} {
   }
   normalize_isodir_adr
 
+  set file_type [isofs_filetype "$isodir_adr"]
+  if {"$file_type" != "d" && "$file_type" != ""} {
+    .isolist insert end "@@@ exists but is not a directory @@@"
+    set isodir_is_pwd 0
+    return ""
+  }
   set disp_en_mem [set_display_msg 0]
   set highest_cmd_sev_mem "$highest_cmd_sev"
   set highest_cmd_sev_msg_mem "$highest_cmd_sev_msg"
@@ -1426,10 +1433,6 @@ proc pick_isodir {} {
     return ""
   }
   set idx [lindex "$selected" 0]
-
-  # <<<
-  # puts stderr "pick_isodir: lindex \$isolist_types $idx = [lindex $isolist_types "$idx"]"
-
   if {[lindex "$isolist_types" "$idx"] != "d"} {
     xorriso_tcltk_errmsg \
        "xorriso-tcltk : SORRY : You may only double-click a directory"
@@ -1517,15 +1520,11 @@ proc isomanip_mv {} {
     } 
   }
 
-  enforce_overwrite_settings
+  enforce_overwrite_settings "isofs"
   reset_highest_cmd_sev
   foreach i "$selected" {
     set name [lindex "$isolist_names" "$i"]
     if {"$isodir_is_pwd" == 0} {
-
-      # <<<
-      # puts stderr "isomanip_mv : isodir_is_pwd = $isodir_is_pwd"
-
       set name [combine_dir_and_name "$isodir_adr" "$name"]
     }
 
@@ -1549,6 +1548,7 @@ proc isomanip_mv {} {
   if {[llength "$selected"] == 1} {
     set isodir_return_name [path_touches_isodir "$target"]
   }
+  browse_iso_refresh
   isodir_return "isomanip_mv"
 }
 
@@ -1590,6 +1590,7 @@ proc isomanip_mkdir {} {
       restore_isolist_selection 
     }
   }
+  browse_iso_refresh
 }
 
 
@@ -1616,6 +1617,7 @@ proc isomanip_rm_r {} {
     }
     send_marked_cmd "-rm_r [make_text_shellsafe "$name"] --"
   }
+  browse_iso_refresh
   isodir_return "isomanip_rm_r"
 }
 
@@ -1785,19 +1787,25 @@ proc calm_drives {} {
 #
 proc burn_write_image {} {
   global burn_write_image_adr burn_write_close outdev_adr outdev_medium_status
-  global outdev_profile burn_write_tao burn_write_defect_mgt
+  global outdev_profile burn_write_tao burn_write_defect_mgt indev_adr
+
+  inquire_dev
+  if {"$indev_adr" != ""} {
+    xorriso_tcltk_errmsg \
+       "xorriso-tcltk : SORRY : You may not have an input drive open when writing an image file"
+    return ""
+  }
 
   if {[assert_outdev "writing an image file"] <= 0} {return ""}
   if {"$burn_write_image_adr" == ""} {
     xorriso_tcltk_errmsg \
-       "xorriso-tcltk : SORRY : You have to set an image file address in the local filesystem first"
+       "xorriso-tcltk : SORRY : You have to set an image file address in the hard disk filesystem first"
     return ""
   }
 
-  if {"$outdev_medium_status" != "blank" && \
-      "$outdev_medium_status" != "appendable"} {
+  if {"$outdev_medium_status" != "blank"} {
     xorriso_tcltk_errmsg \
-      "xorriso-tcltk : SORRY : Medium in output drive is neither blank nor appendable"
+      "xorriso-tcltk : SORRY : You must have a blank medium in the output drive for burning an image data file"
     return ""
   }
   if {[file readable "$burn_write_image_adr"] == 0 || \
@@ -1812,7 +1820,7 @@ proc burn_write_image {} {
 
   set cmd "-as cdrecord -v"
   if {[regexp "^CD" "$outdev_profile"] == 1 && \
-      "$outdev_medium_status" == "appendable"} {
+       ( "$outdev_medium_status" == "appendable" || "$burn_write_tao" == 1 )} {
     set cmd "$cmd padsize=150s"
   }
   set cmd "$cmd dev=[make_text_shellsafe "$outdev_adr"]"
@@ -1881,7 +1889,7 @@ proc refresh_avail {} {
 #
 proc handle_iso_overwriting {target target_ftype from_is_dir
                              selected_adr selected_ftype} {
-  global overwrite_dirs
+  global overwrite_iso_dirs
 
   # >>> Nicer would be:
     # >>> Check if any file will get overwritten. Not only the direct target.
@@ -1894,7 +1902,7 @@ proc handle_iso_overwriting {target target_ftype from_is_dir
                    "'$target'\n\nReally merge with existing ISO directory ?"] \
             != 1} { return "0" }
       } else {
-        if {"$overwrite_dirs" == 1} {
+        if {"$overwrite_iso_dirs" == 1} {
           if {[window_yesno \
                     "'$target'\n\nReally overwrite existing ISO directory ?"] \
               != 1} { return "0" }
@@ -1924,12 +1932,12 @@ proc handle_iso_overwriting {target target_ftype from_is_dir
 #
 proc insert_from {} {
   global insert_from_adr isodir_adr isolist_names isodir_return_name
-  global insert_at_selected insert_underneath overwrite_dirs
+  global insert_at_selected insert_underneath
 
   if {[assert_iso_image 1] == 0} {return ""}
   if {"$insert_from_adr" == ""} {
     xorriso_tcltk_errmsg \
-       "xorriso-tcltk : SORRY : You have to set a source address in the local filesystem first"
+       "xorriso-tcltk : SORRY : You have to set a source address in the hard disk filesystem first"
     return ""
   }
   set selected_ftype ""
@@ -1946,7 +1954,7 @@ proc insert_from {} {
   } else {
     set target "$isodir_adr"
   }
-  set from_is_dir [file isdirectory "$insert_from_adr"]
+  set from_is_dir [localfs_isdir "$insert_from_adr"]
   set name [file tail "$insert_from_adr"]
   if {"$insert_underneath" == 1 || "$from_is_dir" == 0} {
     set target [combine_dir_and_name "$target" "$name"]
@@ -1965,7 +1973,7 @@ proc insert_from {} {
     set preserve_selection 1
   }
   reset_highest_cmd_sev
-  enforce_overwrite_settings
+  enforce_overwrite_settings "isofs"
   send_marked_cmd "-map [make_text_shellsafe "$insert_from_adr"] [make_text_shellsafe "$target"]"
 
   if {"$preserve_selection" == 1} {
@@ -1975,10 +1983,11 @@ proc insert_from {} {
   if {"$preserve_selection" == 1} {
     restore_isolist_selection
   }
+  browse_iso_refresh
 }
 
 
-# Copy a file out of the ISO image model to the local disk filesystem.
+# Copy a file out of the ISO image model to the hard disk filesystem.
 # The meta data stem from the ISO model tree. The content data are usually
 # read from the input drive.
 # Called when button "Extract to disk:" is hit.
@@ -1991,7 +2000,7 @@ proc extract_to {} {
   if {[assert_iso_image 1] == 0} {return ""}
   if {"$extract_to_adr" == ""} {
     xorriso_tcltk_errmsg \
-       "xorriso-tcltk : SORRY : You have to set a target address in the local filesystem first"
+       "xorriso-tcltk : SORRY : You have to set a target address in the hard disk filesystem first"
     return ""
   }
   set sources ""
@@ -2011,8 +2020,43 @@ proc extract_to {} {
   } else {
     set sources [list "$isodir_adr"]
   }
+
+  # Warn of directory mergers. They can cause mess-up on hard disk.
+  set merge_counter 0
+  set merge_source ""
+  set merge_target ""
+  foreach i "$sources" {
+    if {[isofs_filetype "$i"] != "d"} {
+  continue
+    }
+    if {"$extract_underneath" == 1} {
+      set name [file tail "$i"]
+      set target [combine_dir_and_name "$extract_to_adr" "$name"]
+    } else {
+      set target "$extract_to_adr"
+    }
+    if {[localfs_isdir "$target"] == 1} {
+      incr merge_counter
+      set merge_source "$i"
+      set merge_target "$target"
+    }
+  }
+  if {"$merge_counter" > 0} {
+    if {"$sources" == "/" || "$sources" == "{}"} {
+      if {[window_yesno "Really unpack ISO root directory into hard disk directory\n$merge_target\n?"] \
+          != 1} { return "" }
+    } else {
+      set and_others ""
+      if {"$merge_counter" > 1} {
+        set and_others "and do so at $merge_counter more occasions"
+      }
+      if {[window_yesno "Really unpack ISO directory\n [lindex "$sources" 0]\n into hard disk directory\n $merge_target\n$and_others ?"] \
+          != 1} { return "" }
+    }
+  }
+  
   reset_highest_cmd_sev
-  enforce_overwrite_settings
+  enforce_overwrite_settings "localfs"
   set disp_en_mem [set_display_msg 0]
   if {"$extract_auto_chmod" == 1} {
     send_marked_cmd "-osirrox on:sort_lba_on:auto_chmod_on"
@@ -2036,26 +2080,35 @@ proc extract_to {} {
     }
     send_marked_cmd "-extract [make_text_shellsafe "$i"] [make_text_shellsafe "$target"]"
   }
+  browse_tree_populate "localfs"
 }
 
 
 # Send the currently chosen -overwrite settings of the checkbuttons
-# "Overwrite files" and "Overwrite ISO dirs".
+# "Overwrite ISO files", "Overwrite ISO dirs", "Overwrite disk files".
 # Called before operations which could overwrite files in ISO model
-# or in local disk filesystem.
+# or in the hard disk filesystem.
 # I.e. any -overwrite command sent via the "Command:" text field will not
 # be able to override the checkbuttons.
 #
-proc enforce_overwrite_settings {} {
-  global overwrite_files overwrite_dirs
+proc enforce_overwrite_settings {which_fs} {
+  global overwrite_iso_files overwrite_iso_dirs overwrite_disk_files
 
-  if {"$overwrite_files" == 0} {
-    set mode "off"
-  } else {
-    if {"$overwrite_dirs" == 0} {
-      set mode "nondir"
+  if {"$which_fs" == "isofs"} {
+    if {"$overwrite_iso_files" == 0} {
+      set mode "off"
     } else {
+      if {"$overwrite_iso_dirs" == 0} {
+        set mode "nondir"
+      } else {
+        set mode "on"
+      }
+    }
+  } else {
+    if {"$overwrite_disk_files" == 1} {
       set mode "on"
+    } else {
+      set mode "off"
     }
   }
   set disp_en_mem [set_display_msg 0]
@@ -2113,6 +2166,272 @@ proc assert_no_changes {} {
 }
 
 
+# ------ A primitive file tree browser for hard disk filesystem and ISO model 
+
+# Write a directory content list into a Tree widget
+#
+proc browse_tree_fill_dir {tr parent children} {
+
+  if {"$parent" == "/"} {
+    set parent_name root
+  } else {
+    set parent_name "$parent"
+  }
+  if {[$tr exists "$parent_name"] == 0} {return ""}
+
+  $tr delete [$tr nodes "$parent_name"]
+
+  foreach i "$children" {
+    set name [string range "$i" 2 end]
+    set adr [combine_dir_and_name "$parent" "$name"]
+    $tr insert end "$parent_name" "$adr" -text "$name"
+    if {[string range "$i" 0 0] == "d"} {
+      set dir_dummy [combine_dir_and_name "$adr" "dir_dummy"]
+      $tr insert end "$adr" "$dir_dummy" -text "dir_dummy"
+    }
+  }
+}
+
+
+# The command to be executed when the user selects a node.
+#
+proc browse_tree_select {adr_var_name tr selected} {
+  global extract_to_adr insert_from_adr burn_write_image_adr isodir_adr
+  global isomanip_move_target indev_adr outdev_adr
+  global browse_select_is_return
+
+  if {[llength "$selected"] == 0} {
+    set value ""
+  } else {
+    set value [lindex "$selected" 0]
+  }
+  if {"$adr_var_name" == "burn_write_image_adr"} {
+    set burn_write_image_adr "$value"
+    if {"$browse_select_is_return" == 1} {burn_write_image}
+  }
+  if {"$adr_var_name" == "extract_to_adr"} {
+    set extract_to_adr "$value"
+    if {"$browse_select_is_return" == 1} {extract_to}
+  }
+  if {"$adr_var_name" == "insert_from_adr"} {
+    set insert_from_adr "$value"
+    if {"$browse_select_is_return" == 1} {insert_from}
+  }
+  if {"$adr_var_name" == "isodir_adr"} {
+    set isodir_adr "$value"
+    if {"$browse_select_is_return" == 1} {isodir_return "browse_tree_select"}
+  }
+  if {"$adr_var_name" == "isomanip_move_target"} {
+    set isomanip_move_target "$value"
+    # No browse_select_is_return because the field is shared between buttons
+  }
+  if {"$adr_var_name" == "indev_adr"} {
+    set indev_adr "$value"
+    if {"$browse_select_is_return" == 1} {indev_return}
+  }
+  if {"$adr_var_name" == "outdev_adr"} {
+    set outdev_adr "$value"
+    if {"$browse_select_is_return" == 1} {outdev_return}
+  }
+}
+
+
+# The command to be executed when the user closes a directory node.
+# It replaces the directory content list by a single dummy item.
+#
+proc browse_tree_close_dir {tr name} {
+  browse_tree_fill_dir $tr "$name" "{? dir_dummy}"
+}
+
+
+# Delete the old content of the browse window and display the freshly
+# obtained current state down to the current address in the field variable.
+#
+proc browse_tree_populate {which_fs} {
+  global browse_disk_window_var browse_iso_window_var
+  global browse_iso_window_is_active browse_disk_window_is_active
+  global extract_to_adr insert_from_adr burn_write_image_adr isodir_adr
+  global isomanip_move_target indev_adr outdev_adr
+  global browse_select_is_return
+
+  if {"$which_fs" == "isofs"} {
+    if {"$browse_iso_window_is_active" == 0} {return ""}
+    set w {.browse_iso_window}
+    set open_dir_cmd "browse_iso_open_dir"
+    set adr_var "$browse_iso_window_var"
+  } else {
+    if {"$browse_disk_window_is_active" == 0} {return ""}
+    set w {.browse_disk_window}
+    set open_dir_cmd "browse_disk_open_dir"
+    set adr_var "$browse_disk_window_var"
+  }
+
+  # Variable indirection
+  eval set adr $$adr_var
+
+  # Install root level
+  $open_dir_cmd $w.tree "/" 
+
+  # Set $adr as current address
+  set comps [split "$adr" "/"]
+  # Install the stack of directories above current address
+  set path "/"
+  foreach i "$comps" {
+    if {"$i" == ""} {
+  continue
+    }
+    set path [combine_dir_and_name "$path" "$i"]
+    $open_dir_cmd $w.tree "$path" 
+    catch {
+      $w.tree opentree "$path" 0
+      $w.tree see "$path"
+    }
+  }
+}
+
+
+# Destroy the hard disk browser pop-up window.
+# 
+proc destroy_browse_disk {w} {
+  global browse_disk_window_is_active 
+
+  if {"$w" != "" && "$browse_disk_window_is_active" == 1} {
+    destroy "$w"
+  }
+  set browse_disk_window_is_active 0
+}
+
+
+# The command to be executed when the user opens a directory node in
+# the hard disk filesystem.
+#
+proc browse_disk_open_dir {tr name} {
+  if {[localfs_isdir "$name"] != 1} {return ""}
+  set lslist [localfs_ls "$name"]
+  browse_tree_fill_dir $tr "$name" "$lslist"
+}
+
+
+# Refresh the content of a possibly displayed tree browser for hard disk
+#
+proc browse_disk_refresh {} {
+  browse_tree_populate "localfs"
+}
+
+
+# The command to be executed when the user opens a directory node in
+# the ISO model.
+#
+proc browse_iso_open_dir {tr name} {
+  if {[isofs_filetype "$name"] != "d"} {return ""}
+  set lslist [isofs_ls "$name"]
+  browse_tree_fill_dir $tr "$name" "$lslist"
+}
+
+
+# Destroy the ISO browser pop-up window.
+# 
+proc destroy_browse_iso {w} {
+  global browse_iso_window_is_active 
+
+  if {"$w" != "" && "$browse_iso_window_is_active" == 1} {
+    destroy "$w"
+  }
+  set browse_iso_window_is_active 0
+}
+
+
+# Refresh the content of a possibly displayed tree browser for ISO model
+#
+proc browse_iso_refresh {} {
+  browse_tree_populate "isofs"
+}
+
+
+# Open a file browser window for hard disk filesystem or ISO model
+#
+proc browse_tree {adr_var which_fs} {
+  upvar $adr_var adr
+  global have_bwidget browse_disk_window_is_active browse_iso_window_is_active
+  global browse_disk_window_var browse_iso_window_var
+
+  set button_color "grey"
+
+  set old_geometry ""
+  if {"$which_fs" == "isofs"} {
+    set w {.browse_iso_window}
+    set window_is_active "$browse_iso_window_is_active"
+    set title_name "xorriso-tcltk ISO filesystem browser"
+    set open_dir_cmd "browse_iso_open_dir"
+    set destroy_cmd "destroy_browse_iso"
+    if {"$browse_iso_window_var" != "$adr_var" && "$window_is_active" == 1} {
+      set old_geometry [wm geometry $w]
+      destroy_browse_iso $w
+      set window_is_active 0
+    }
+    set browse_iso_window_var "$adr_var"
+    set browse_iso_window_is_active 1
+  } else {
+    set w {.browse_disk_window}
+    set window_is_active "$browse_disk_window_is_active"
+    set title_name "xorriso-tcltk disk filesystem browser"
+    set open_dir_cmd "browse_disk_open_dir"
+    set destroy_cmd "destroy_browse_disk"
+    if {"$browse_disk_window_var" != "$adr_var" && "$window_is_active" == 1} {
+      set old_geometry [wm geometry $w]
+      destroy_browse_disk $w
+      set window_is_active 0
+    }
+    set browse_disk_window_var "$adr_var"
+    set browse_disk_window_is_active 1
+  }
+  set re_use_widgets 0
+  if {"$window_is_active" == 0} {
+    toplevel $w -borderwidth 10 -class Browse
+    wm title $w "$title_name"
+    if {"$old_geometry" != ""} {
+      wm geometry $w "$old_geometry"
+    }
+  } else { 
+    set re_use_widgets 1
+  }
+  if {"$re_use_widgets" == 0} {
+    # BWidget Tree
+    frame $w.tree_frame
+    frame $w.tree_frame_y
+    Tree $w.tree -width 80 \
+                 -opencmd "$open_dir_cmd $w.tree" \
+                 -closecmd "browse_tree_close_dir $w.tree" \
+                 -selectcommand "browse_tree_select $adr_var" \
+                 -yscrollcommand "$w.treescroll_y set" \
+                 -xscrollcommand "$w.treescroll_x set"
+    scrollbar $w.treescroll_y -command "$w.tree yview"
+    scrollbar $w.treescroll_x -orient horizontal -command "$w.tree xview "
+    pack $w.tree -in $w.tree_frame_y -side left  -expand 1 -fill both
+    pack $w.treescroll_y -in $w.tree_frame_y -side left -fill y
+    pack $w.tree_frame_y $w.treescroll_x -in $w.tree_frame \
+                                         -side top -expand 1 -fill both
+
+# >>> BAUSTELLE
+
+    # >>> Need key bindings for navigation and selection
+
+    # >>> Need help bindings
+
+    button $w.close -text "Close" -command "$destroy_cmd $w" \
+                    -background "$button_color"
+
+    # >>> Need "Up" button
+
+    pack $w.tree_frame $w.close -side top
+
+  } else {
+    raise $w
+  }
+  browse_tree_populate "$which_fs"
+}
+
+ 
 # ------ GUI display procedures ----
 
 
@@ -2296,33 +2615,47 @@ proc window_ack {question button_color where} {
 # Destroy the help pop-up window.
 #
 proc destroy_help {w} {
-  global help_window_is_active
+  global help_window_is_active help_window_has_scroll
 
   if {"$w" != ""} {
     destroy "$w"
   }
   set help_window_is_active 0
+  set help_window_has_scroll 0
+}
+
+
+proc surround_text {text} {
+  return "\n\n  [string map {\n "\n  "} "$text"]\n"
 }
 
 
 # Pop-up a window which shows a help text and a Close button.
 #
 proc window_help {about_what button_color} {
-  global help_window_is_active
+  global help_window_is_active help_window_lines help_window_has_scroll
+  global help_window_border_width
   global .help_window
-
-  set color "#F0F0F0"
-
-  set re_use_widgets 0
   set w {.help_window}
+
+  # Giving the help text some distance from the border decorations
+  set line_width 82
+  set helptext "\n\n  [string map {\n "\n  "} [tell_helptext "$about_what"]]\n"
+
+  if {[count_newlines "$helptext"] >= "$help_window_lines"} {
+    if {"$help_window_is_active" == 1 && "$help_window_has_scroll" == 0} {
+       destroy_help $w
+    }
+    set help_window_has_scroll 1
+  }
+  set re_use_widgets 0
   if {"$help_window_is_active" == 0} {
-    toplevel $w -borderwidth 20 -class Help
+    toplevel $w -borderwidth "$help_window_border_width" -class Help
     wm title $w "xorriso-tcltk help text"
     set help_window_is_active 1
   } else {
     set re_use_widgets 1
   }
-  set helptext [tell_helptext "$about_what"] 
   if {"$re_use_widgets" == 1} {
     $w.text configure -state normal
     $w.text delete 1.0 end
@@ -2332,12 +2665,24 @@ proc window_help {about_what button_color} {
     # wm geometry $w +0+0
     set destroy_cmd "destroy_help $w"
 
-    text $w.text -width 80 -height 20 -relief flat -borderwidth 0
+    frame $w.text_frame
+    text $w.text -width "$line_width" -height "$help_window_lines" \
+                 -relief flat -borderwidth 0
     $w.text insert end "$helptext"
+    pack $w.text -in $w.text_frame -side left  -expand 1 -fill both
+    if {"$help_window_has_scroll" == 1} {
+      scrollbar $w.scroll_y -command "$w.text yview"
+      $w.text configure -yscrollcommand "$w.scroll_y set"
+      bind_listbox_keys $w.text "$help_window_lines" "text"
+      pack $w.scroll_y -in $w.text_frame -side left -fill y
+    } 
+
     button $w.close -text "Close" -command "$destroy_cmd" \
                     -background "$button_color"
-    pack $w.text -side top -expand 1 -fill both
-    pack $w.close -side top 
+    pack $w.text_frame -side top -expand 1 -fill both
+    frame $w.middle_spacer -height 6
+    frame $w.bottom_spacer -height 6
+    pack $w.middle_spacer $w.close $w.bottom_spacer -side top 
   }
   $w.text configure -state disabled
 }
@@ -2363,6 +2708,26 @@ proc display_busy {state} {
 }
 
 
+# Tries to make use of the BWidget package for getting its Tree widget
+#
+proc check_for_bwidget {} {
+  global have_bwidget bwidget_version
+
+  if {"$have_bwidget" == 0} {
+    catch {
+      set bwidget_version [package require BWidget]
+      set have_bwidget 1
+    }
+  }
+}
+
+
+proc browser_dummy {} {
+  window_ack \
+    "The file browser cannot be used because Tcl/Tk package \"BWidget\" is not loaded" "grey" "toplevel"
+}
+
+
 # ------ Building GUI components ------
 
 # ------ GUI layout parameters ------
@@ -2394,6 +2759,12 @@ set export_msg_selection true
 # Wether the item lists shall export their selection
 set export_selection false
 
+# The number of lines in the display of the help texts
+set help_window_lines 18
+
+# The distance of the help text from the help window border
+set help_window_border_width 0
+
 
 # -------- GUI definition procedures
 
@@ -2405,6 +2776,8 @@ proc init_gui {} {
   global .isobox .localfs
   global main_framerelief main_borderwidth
 
+  check_for_bwidget
+
   # Main grouping frames
   frame .connection_block \
         -relief "$main_framerelief" -borderwidth "$main_borderwidth"
@@ -2521,14 +2894,10 @@ proc init_msgbox {} {
   listbox .msglist -height $msglist_lines -selectmode extended \
                    -yscrollcommand ".msgscroll set" \
                    -exportselection $export_msg_selection
-  bind_listbox_keys ".msglist" "$msglist_lines" 
+  bind_listbox_keys ".msglist" "$msglist_lines" "listbox"
   bind_help .msglist "message box"
   set msglist_running 1
   foreach i "$pre_msglist" {
-
-    # <<<
-    # puts stderr "init_msgbox : pre_msglist : $i"
-
     display_msg "$i"
   }
   scrollbar .msgscroll -command ".msglist yview"
@@ -2618,7 +2987,7 @@ proc init_drivebox {} {
   listbox .drivelist -height $drivelist_lines -selectmode extended \
                      -yscrollcommand ".drivescroll set" \
                      -exportselection $export_selection
-  bind_listbox_keys ".drivelist" "$drivelist_lines" 
+  bind_listbox_keys ".drivelist" "$drivelist_lines" "listbox"
   bind_help .drivelist "drivelist"
   scrollbar .drivescroll -command ".drivelist yview"
 
@@ -2693,11 +3062,18 @@ proc init_indev {} {
   bind_help .indev_label "Input drive or image"
   entry .indev_entry -width 40 -relief sunken -bd 1 \
                      -textvariable indev_adr
+
   bind_entry_keys .indev_entry {indev_return}
   bind_help .indev_entry  "Input drive or image"
   label .indev_summary -width 65 -text "" -relief ridge -borderwidth 2
   bind_help .indev_summary  "input drive info"
-  pack .indev_eject .indev_label .indev_entry .indev_summary \
+  create_browser_button .indev_browse_button \
+                        "indev_adr" "localfs" "Browse disk (indev)"
+
+  pack .indev_eject .indev_label .indev_entry \
+       -in .indev -side left -expand 1 -fill both
+  pack .indev_browse_button -in .indev -side left 
+  pack .indev_summary \
        -in .indev -side left -expand 1 -fill both
 }
 
@@ -2718,9 +3094,14 @@ proc init_outdev {} {
                       -textvariable outdev_adr
   bind_entry_keys .outdev_entry {outdev_return}
   bind_help .outdev_entry "Output drive or image"
+  create_browser_button .outdev_browse_button \
+                        "outdev_adr" "localfs" "Browse disk (outdev)"
   label .outdev_summary -width 65 -text "" -relief ridge -borderwidth 2
   bind_help .outdev_summary "output drive info"
-  pack .outdev_eject .outdev_label .outdev_entry .outdev_summary \
+  pack .outdev_eject .outdev_label .outdev_entry \
+       -in .outdev -side left -expand 1 -fill both
+  pack .outdev_browse_button -in .outdev -side left 
+  pack .outdev_summary \
        -in .outdev -side left -expand 1 -fill both
 }
 
@@ -2752,6 +3133,8 @@ proc init_burn {} {
                                 -textvariable burn_write_image_adr
   bind_entry_keys .burn_write_image_entry {burn_write_image}
   bind_help .burn_write_image_entry "Burn image file:"
+  create_browser_button .burn_image_browse_button \
+                    "burn_write_image_adr" "localfs" "Browse disk (burn image)"
   checkbutton .burn_write_close -text "Close" \
                                 -indicatoron 1 -selectcolor "" \
                                 -relief ridge -borderwidth 2 \
@@ -2775,6 +3158,7 @@ proc init_burn {} {
        .burn_write_defect_mgt \
        .burn_write_image .burn_write_image_entry \
        -in .burn -side left -expand 1 -fill both
+  pack .burn_image_browse_button -in .burn -side left
 }
 
 
@@ -2795,6 +3179,8 @@ proc init_isobox {} {
                       -textvariable isodir_adr
   bind_entry_keys .isodir_entry {isodir_return "isodir_entry"}
   bind_help .isodir_entry "ISO directory:"
+  create_browser_button .isodir_browse_button \
+                        "isodir_adr" "isofs" "Browse ISO (isodir)"
   button .isodir_verify -text "Verify" -command {isodir_verify}
   bind_help .isodir_verify "Verify"
   button .isodir_up -text "Up" -command {isodir_up}
@@ -2805,7 +3191,7 @@ proc init_isobox {} {
        -in .isodir -side left
   pack .isodir_entry \
        -in .isodir -side left -expand 1 -fill both
-  pack .isodir_up2 .isodir_verify \
+  pack .isodir_browse_button .isodir_up2 .isodir_verify \
        -in .isodir -side left
 
   frame .isolistbox -borderwidth 0
@@ -2814,7 +3200,7 @@ proc init_isobox {} {
                    -xscrollcommand ".isoscroll_x set" \
                    -exportselection $export_selection
   bind_help .isolist "isolist"
-  bind_listbox_keys ".isolist" "$isolist_lines" 
+  bind_listbox_keys ".isolist" "$isolist_lines" "listbox"
   scrollbar .isoscroll_y -command ".isolist yview"
   scrollbar .isoscroll_x -orient horizontal -command ".isolist xview"
   pack .isolist     -in .isolistbox -side left  -expand 1 -fill both
@@ -2859,16 +3245,20 @@ proc init_isomanip {} {
   # bind_entry_keys .isomanip_move_target {isomanip_mv}
   bind_entry_keys .isomanip_move_target ""
   bind_help .isomanip_move_target "rename and mkdir target"
+  create_browser_button .isomanip_move_target_button \
+                      "isomanip_move_target" "isofs" "Browse ISO (move target)"
   pack .isomanip_prefix .isomanip_verify_button .isomanip_rm_r_button \
-       .isomanip_move_button .isomanip_move_target .isomanip_mkdir_button \
+       .isomanip_move_button .isomanip_move_target \
+       -in .isomanip_move -side left -expand 1 -fill both
+  pack .isomanip_move_target_button -in .isomanip_move -side left
+  pack .isomanip_mkdir_button \
        -in .isomanip_move -side left -expand 1 -fill both
-
   pack .isomanip_move \
        -in .isomanip -side top -expand 1 -fill both
 }
 
 
-# The means for interaction of ISO image and local filesystem.
+# The means for interaction of ISO image and hard disk filesystem.
 #
 proc init_localfs {} {
   global borderwidth
@@ -2892,8 +3282,6 @@ proc init_extract {} {
   global .extract_button .extract_frame .extract_entry .extract_from_selected
   global .extract_underneath 
 
-  # >>> should be some file browser instead of a button-entry pair
-
   frame .extract_frame -borderwidth 0
   button .extract_button -text "Extract to disk:" \
                          -width 17 \
@@ -2903,6 +3291,8 @@ proc init_extract {} {
                        -textvariable "extract_to_adr"
   bind_entry_keys .extract_entry {extract_to}
   bind_help .extract_entry "Extract to disk:"
+  create_browser_button .extract_browse_button \
+                        "extract_to_adr" "localfs" "Browse disk (extract)"
   checkbutton .extract_underneath -text "Underneath" \
                                   -indicatoron 1 -selectcolor "" \
                                   -relief ridge -borderwidth 2 \
@@ -2920,28 +3310,29 @@ proc init_extract {} {
        -in .extract_frame -side left -expand 1 -fill both
   pack .extract_from_selected .extract_underneath \
        -in .extract_frame -side right
+  pack .extract_browse_button -in .extract_frame -side right
 }
 
 
 # Some controls which apply to insertion, extraction, or both.
 #
 proc init_localfs_aux {} {
-  global borderwidth
+  global borderwidth have_bwidget
   global .localfs_aux_frame
-  global .overwrite_files_button .overwrite_dir_button .extract_auto_chmod
+  global .overwrite_iso_files_button .overwrite_dir_button .extract_auto_chmod
   global .avail_label .avail_label_frame .avail_button
 
   frame .localfs_aux_frame -borderwidth 0
-  checkbutton .overwrite_files_button -text "Overwrite files" \
+  checkbutton .overwrite_iso_files_button -text "Overwrite ISO files" \
                                       -indicatoron 1 -selectcolor "" \
                                       -relief ridge -borderwidth 2 \
-                                      -variable overwrite_files \
+                                      -variable overwrite_iso_files \
                                       -onvalue 1 -offvalue 0
-  bind_help .overwrite_files_button "Overwrite files"
+  bind_help .overwrite_iso_files_button "Overwrite ISO files"
   checkbutton .overwrite_dir_button -text "Overwrite ISO dirs" \
                                       -indicatoron 1 -selectcolor "" \
                                       -relief ridge -borderwidth 2 \
-                                      -variable overwrite_dirs \
+                                      -variable overwrite_iso_dirs \
                                       -onvalue 1 -offvalue 0
   bind_help .overwrite_dir_button "Overwrite ISO dirs"
   checkbutton .extract_auto_chmod   -text "Enforce disk dir write access" \
@@ -2950,8 +3341,24 @@ proc init_localfs_aux {} {
                                       -variable extract_auto_chmod \
                                       -onvalue 1 -offvalue 0
   bind_help .extract_auto_chmod "Enforce disk dir write access"
-  pack .overwrite_files_button .overwrite_dir_button .extract_auto_chmod \
+  checkbutton .overwrite_disk_files_button -text "Overwrite disk files" \
+                                      -indicatoron 1 -selectcolor "" \
+                                      -relief ridge -borderwidth 2 \
+                                      -variable overwrite_disk_files \
+                                      -onvalue 1 -offvalue 0
+  bind_help .overwrite_disk_files_button "Overwrite disk files"
+  pack .overwrite_iso_files_button .overwrite_dir_button .extract_auto_chmod \
+       .overwrite_disk_files_button \
        -in .localfs_aux_frame -side left
+  if {"$have_bwidget" == 1} {
+    checkbutton .browse_select_is_return -text "File browser Return" \
+                                        -indicatoron 1 -selectcolor "" \
+                                        -relief ridge -borderwidth 2 \
+                                        -variable "browse_select_is_return" \
+                                        -onvalue 1 -offvalue 0
+    bind_help .browse_select_is_return "File browser Return"
+    pack .browse_select_is_return -in .localfs_aux_frame -side left
+  }
 
   button .avail_button -text "Refresh avail:" \
                              -command {refresh_avail}
@@ -2972,8 +3379,6 @@ proc init_insert {} {
   global .insert_button .insert_from_frame .insert_entry .insert_at_selected
   global .insert_underneath .insert_frame
 
-  # >>> should be some file browser instead of a button-entry pair
-
   frame .insert_frame -borderwidth 0
   frame .insert_from_frame -borderwidth 0
   button .insert_button -text "Insert from disk:" \
@@ -2984,6 +3389,8 @@ proc init_insert {} {
                       -textvariable "insert_from_adr"
   bind_entry_keys .insert_entry {insert_from}
   bind_help .insert_entry "Insert from disk:"
+  create_browser_button .insert_browse_button \
+                        "insert_from_adr" "localfs" "Browse disk (insert)"
   checkbutton .insert_underneath -text "Underneath" \
                                  -indicatoron 1 -selectcolor "" \
                                  -relief ridge -borderwidth 2 \
@@ -2999,6 +3406,7 @@ proc init_insert {} {
   pack .insert_button -in .insert_from_frame -side left
   pack .insert_entry \
        -in .insert_from_frame -side left -expand 1 -fill both
+  pack .insert_browse_button -in .insert_from_frame -side left
   pack .insert_at_selected .insert_underneath \
        -in .insert_from_frame -side right
   pack .insert_from_frame -in .insert_frame -side left -expand 1 -fill both
@@ -3007,7 +3415,7 @@ proc init_insert {} {
 
 # Set common behavior of listboxes in respect to focus and navigation keys.
 #
-proc bind_listbox_keys {box height} {
+proc bind_listbox_keys {box height what_widget} {
   global click_to_focus
 
   if {"$click_to_focus" == 1} {
@@ -3019,14 +3427,12 @@ proc bind_listbox_keys {box height} {
   }
 
   # No underlining
-  $box configure -activestyle none
+  if {"$what_widget" == "listbox"} {
+    $box configure -activestyle "none"
+  }
 
   # Need to evaluate all $box and $height at bind-time. Thus "-quotes.
   bind $box <Any-KeyPress> "
-
-    # <<<
-    # puts stderr \"bind_updown_keys: K = '%K'\"
-
     if {\"%K\" == \"Up\"} {
       $box yview scroll \"-1\" units
     }
@@ -3035,9 +3441,11 @@ proc bind_listbox_keys {box height} {
     }
     if {\"%K\" == \"Prior\"} {
       $box yview scroll -[expr \"$height\" - 1] units
+#      $box yview scroll -1 pages
     }
     if {\"%K\" == \"Next\"} {
       $box yview scroll [expr \"$height\" - 1] units
+#      $box yview scroll 1 pages
     }
     if {\"%K\" == \"Home\"} {
       $box yview 0
@@ -3045,6 +3453,9 @@ proc bind_listbox_keys {box height} {
     if {\"%K\" == \"End\"} {
       $box yview end
     }
+
+    # >>> Do i need this ?
+      # >>> For now: yes. It prevents double scrolling by PgUp PgDown
     # Prevent other bindings from being performed
     break
   "
@@ -3072,16 +3483,175 @@ proc bind_help {to_what help_name} {
 }
 
 
+# Create a "/" button and wire it with variable, fileystem type, and help text.
+#
+proc create_browser_button {button_name var_name which_fs help_name} {
+  global have_bwidget
+
+  if {"$have_bwidget" == 1} {
+    button $button_name -text "/" -command "browse_tree $var_name $which_fs"
+    bind_help $button_name "$help_name"
+  } else {
+    button $button_name -text "/" -command "browser_dummy"
+    if {"$which_fs" == "localfs"} {
+      bind_help $button_name "Browse disk (dummy)"
+    } else {
+      bind_help $button_name "Browse ISO (dummy)"
+    }
+  }
+}
+
+
 # The central storage for help texts.
 #
 proc tell_helptext {what} {
-  global own_version argv0
+  global own_version argv0 bwidget_version
 
   if {"$what" == "Help"} {
     return \
 "For getting particular help texts:
 
-Click the rightmost mouse button on any button, list, or text field of the GUI. 
+  Click the rightmost mouse button on any button, list box, or text field. 
+
+For a help text about startup options of this frontend, execute in a shell:
+
+  $argv0 --help
+
+For background info about xorriso and its commands, execute in a shell:
+
+  man xorriso
+
+-----------------------------------------------------------------------------
+
+The GUI window is separated into three main areas:
+
+- The area for connection to xorriso
+  - shows xorriso messages,
+  - offers some general activities,
+  - displays the \"ready/busy\" state of the connection,
+  - and allows to toggle xorriso commands into the \"Command:\" field.
+
+- The area for management of drives and ISO image data files
+  - allows to scan for optical drives,
+  - to aquire them and load their ISO directory tree,
+  - to aquire ISO image files from hard disk as pseudo drives like DVD+RW,
+  - to blank CD-RW, DVD=RW, DVD+RW, BD-RE and format DVD-RW, BD-R,
+  - to trigger writing of ISO sessions (which get defined in the third area),
+  - and to burn image data files from hard disk to optical media.
+
+- The area for inspection, manipulation, and exploitation of the ISO model
+  - allows to insert directories and files from hard disk into the ISO model,
+  - to delete and rename file objects in the ISO model,
+  - to verify data files of loaded ISO directory trees by MD5,
+  - to extract directories and files from ISO filesystem to hard disk.
+  
+-----------------------------------------------------------------------------
+                              Some Use Cases
+-----------------------------------------------------------------------------
+
+- Burn a directory as only content onto a CD, DVD or BD
+- Write a directory as only content to an ISO image data file on hard disk
+- Burn an image data file from hard disk onto CD, DVD or BD
+- Add more data to an appendable medium or to an ISO image data file
+- Extract a directory tree from an ISO filesystem to hard disk
+
+-----------------------------------------------------------------------------
+
+            Burn a directory as only content onto a CD, DVD or BD
+
+- Click the \"Scan for drives\" button in the middle area.
+- Select a drive and click the \"Pick output drive\" button.
+- If the information field in the \"Output drive or Image\" line begins by
+  \"appendable\" or \"closed\" and if the medium is CD-RW, DVD-RW, DVD+RW, or
+  BD-RE then click the \"Blank\" button to erase the old data.
+  (Blanking of \"DVD-RW sequential recording\" will last very long.)
+- Go to the \"Insert from disk:\" line in the lower area.
+  Either toggle in the address of the hard disk directory,
+  or click on the \"/\" button to the right of the text field to get
+  a file browser.
+- Hit the Return key or click on a name in the browser to schedule
+  the disk directory for writing to the medium.
+  (You may of course insert several directories or files that way.)
+- Click the \"Write ISO session\" button in the middle area.
+  Confirm in the \"yes/no\" window that pops up.
+  Burning will begin (or refuse on unsuitable medium status).
+- When the \"busy\" field displays \"ready\" again, you may click \"Eject\".
+  Desktop drives should then put out the tray with the medium.
+
+-----------------------------------------------------------------------------
+
+   Write a directory as only content to an ISO image data file on hard disk
+
+- Toggle the name of the intended data file in the text field of the
+  \"Output drive or image\" line and hit the Return key.
+- If the information field in the \"Output drive or Image\" line begins by
+  \"appendable\" or \"closed\" then you addressed an existing data file.
+  Warning: Applying the \"Blank\" button to it would damage its content !
+  You probably do not want this in this special use case.
+- Go to the \"Insert from disk:\" line in the lower area.
+  Continue like in the above description for CD, DVD, and BD media.
+
+-----------------------------------------------------------------------------
+
+         Burn an image data file from hard disk onto CD, DVD or BD
+
+- Click the \"Scan for drives\" button in the middle area.
+- Select a drive and click the \"Pick output drive\" button.
+- If the information field in the \"Output drive or Image\" line begins by
+  \"appendable\" or \"closed\" and if the medium is CD-RW, DVD-RW, DVD+RW, or
+  BD-RE then click the \"Blank\" button to erase the old data.
+  (Blanking of \"DVD-RW sequential recording\" will last very long.)
+- Go to the text field beneath the \"Burn image file:\" button and toggle
+  the address of the image file. Or click on the \"/\" button to the right
+  of the field to get a file browser.
+- Hit the Return key in the text field or click on a name in the browser
+  to initiate the burn run.
+  Confirm in the \"yes/no\" window that pops up.
+- When the \"busy\" field displays \"ready\" again, you may click \"Eject\".
+  Desktop drives should then put out the tray with the medium.
+
+-----------------------------------------------------------------------------
+
+      Add more data to an appendable medium or to an ISO image data file
+
+- Like above, \"Scan for drives\" but click button \"Pick drive for both roles\"
+  in order to load the directory tree of the existing ISO filesystem.
+  For an ISO image data file, bring its name into the input fields of both
+  lines \"Input drive or image\" and \"Output drive or image\".
+  You should now see in both info fields texts which begin by \"appendable\".
+- Go to the \"Insert from disk:\" line in the lower area.
+  Use the means described in the first use case to add more directories or
+  data files.
+- If you are interested in \"Delete\" or \"Rename to:\" buttons in the
+  bottom line of the GUI: Click them by the rightmost mouse button to see
+  their help texts.
+- When all intended changes are done: Click \"Write ISO session\" and
+  confirm in the \"yes/no\" window.
+
+-----------------------------------------------------------------------------
+
+         Extract a directory tree from an ISO filesystem to hard disk
+
+- Like above, \"Scan for drives\" but click button \"Pick input drive\"
+  in order to load the directory tree of the existing ISO filesystem.
+  For an ISO image data file, bring its name into the input field of the
+  lines \"Input drive or image\" and \"Output drive or image\".
+  You should now see in both info fields texts which begin by \"appendable\".
+- Go to the \"ISO directory:\" line in the lower area.
+  Either toggle in the address of the directory you want to extract or
+  click the \"/\" button to get a file browser.
+- Hit the Return key or click on a name in the browser to determine
+  the ISO directory for writing to the medium.
+- Go to the \"Extract to disk:\" line in the lower area.
+  Either toggle in the address of the hard disk directory,
+  or click on the \"/\" button to the right of the text field to get
+  a file browser.
+- Hit the Return key or click on a name in the browser to initiate the
+  extraction run.
+  If a \"yes/no\" window pops up, consider well whether you are up to
+  to shooting your own foot right now.
+  Enable the \"Overwrite disk files\" switch only if you are really
+  sure that the files from ISO are better than the ones on hard disk.
 
 -----------------------------------------------------------------------------
 
@@ -3091,14 +3661,11 @@ xorriso in dialog mode.
 It demonstrates some of xorriso's multi-session features with ISO 9660
 filesystems on optical media (CD, DVD, BD) or in disk files.
 
+Dependencies:
+  xorriso, Tcl language, Tk GUI toolkit, optionally Tcl/Tk package BWidget
+
 Copyright (C) 2012, Thomas Schmitt <scdbackup@gmx.net>, libburnia-project.org
-Provided under GNU GPL version 2 or later.
-
------------------------------------------------------------------------------
-
-For a help text about startup options of this frontend, execute:
-
-  $argv0 --help"
+Provided under GNU GPL version 2 or later."
   }
   if {"$what" == "End"} {
     return \
@@ -3399,7 +3966,13 @@ check-reading shall be enabled when writing to formatted BD-R or BD-RE.
 burn a data file from hard disk onto the output drive.
 The address of the disk file is taken from the neighboring text field.
 
-The medium in the drive may be blank or appendable."
+The medium in the drive must be blank.
+
+(It is well possible to burn image files to appendable media. But the
+image needs to be prepared for the address offset. Who can do that can
+as well use one of the command line tools for burning the result. E.g.
+  xorriso -as cdrecord -v dev=/dev/sr0 -multi stream_recording=32s image.iso
+)"
   }
   if {"$what" == "Extract to disk:"} {
     return \
@@ -3410,6 +3983,86 @@ underneath \"ISO directory:\".
 This copies the selected files or directory trees from the input drive
 to the address on hard disk which is given by the text field right of
 the button."
+  }
+  if {"$what" == "Browse disk (extract)"} {
+    return \
+"The \"/\" button in the \"Extract to disk:\" line pops up a file tree
+browser to select a target address in the hard disk filesystem.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"Extract to disk:\"
+field."
+  }
+  if {"$what" == "Browse disk (burn image)"} {
+    return \
+"The \"/\" button beneath the \"Burn image file\" field pops up a file
+tree browser to select a source address in the hard disk filesystem.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"Burn image file\"
+field."
+  }
+  if {"$what" == "Browse disk (insert)"} {
+    return \
+"The \"/\" button beneath the \"Insert from disk\" field pops up a file
+tree browser to select a source address in the hard disk filesystem.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"Insert from disk\"
+field."
+
+  }
+  if {"$what" == "Browse disk (indev)"} {
+    return \
+"The \"/\" button in the \"Input drive or image\" line pops up a file tree
+browser to select a source address in the hard disk filesystem.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"Input drive or image\"
+field."
+  }
+  if {"$what" == "Browse disk (outdev)"} {
+    return \
+"The \"/\" button in the \"Output drive or image\" line pops up a file tree
+browser to select a source address in the hard disk filesystem.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"Output drive or image\"
+field."
+  }
+  if {"$what" == "Browse ISO (isodir)"} {
+    return \
+"The \"/\" button in the \"ISO directory\" line pops up a file tree
+browser to select the current directory in the ISO filesystem model.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into effect with the \"ISO directory\"
+field."
+  }
+  if {"$what" == "Browse ISO (move target)"} {
+    return \
+"The \"/\" button in the \"ISO selection:\" line pops up a file tree
+browser to select the current directory in the ISO filesystem model.
+
+Click on the \"+\" resp. \"-\" nodes to open resp. close directories.
+Click on an item to bring it into the address field for \"Rename to:\"
+and \"Make dir\"."
+  }
+  if {"$what" == "Browse disk (dummy)"} {
+    return \
+"Normally this button would start a file browser to select a file or
+directory on hard disk.
+
+But the browser cannot be displayed because Tcl/Tk package \"BWidget\"
+is not loaded."
+  }
+  if {"$what" == "Browse ISO (dummy)"} {
+    return \
+"Normally this button would start a file browser to select a file or
+directory in the ISO model.
+
+But the browser cannot be displayed because Tcl/Tk package \"BWidget\"
+is not loaded."
   }
   if {"$what" == "Underneath (extract)"} {
     return \
@@ -3439,10 +4092,10 @@ The last command will fail because /tmp/from_iso already exists as directory."
 or only the selected items shall be copied to hard disk.
 "
   }
-  if {"$what" == "Overwrite files"} {
+  if {"$what" == "Overwrite ISO files"} {
     return \
-"The \"Overwrite files\" switch controls whether existing files may be
-overwritten in the ISO image or by extraction on hard disk.
+"The \"Overwrite ISO files\" switch controls whether existing files may be
+overwritten in the ISO image.
 
 The frontend program will only detect the most obvious name collisions,
 but xorriso will reliably refuse to overwrite files if this is banned."
@@ -3458,17 +4111,37 @@ hit directories."
   }
   if {"$what" == "Enforce disk dir write access"} {
     return \
-"The \"Enforce disk dir write access\" switch enables the options -osirrox
+"The \"Enforce disk dir write access\" switch enables the -osirrox options
 \"auto_chmod_on\" and \"sort_lba_on\" which influence file extraction.
 
 \"auto_chmod_on\" allows xorriso to give itself temporariy w-permission to
-all disk directories which are owned by the xorriso user. This is not
-without dangers, of course, but comes in handy with restoring of backups.
+all disk directories which are owned by the xorriso user.
+
+This is DANGEROUS, of course, but comes in handy with restoring of backups.
 
 Option \"sort_lba_on\" reduces head-moves of optical drives and thus can
 speed up extraction substantially. It is bound to \"auto_chmod_on\" because
 else it might get in trouble when restoring ISO directories which offer
 no w-permission."
+  }
+  if {"$what" == "Overwrite disk files"} {
+    return \
+"The \"Overwrite disk files\" switch controls whether existing files may be
+overwritten by extraction on hard disk.
+
+This is DANGEROUS, of course, but comes in handy with restoring of backups.
+
+The frontend program will only detect the most obvious name collisions,
+but xorriso will reliably refuse to overwrite files if this is banned."
+  }
+  if {"$what" == "File browser Return"} {
+    return \
+"The \"File browser Return\" switch controls whether a selection click in
+the file browser shall also hit the Return key after setting the
+selected address into the text input field. 
+
+If the switch is disabled, then the address gets written into the field
+but no further action is triggered."
   }
   if {"$what" == "Refresh avail:"} {
     return \
@@ -3655,6 +4328,7 @@ proc count_newlines {text} {
       set rest [string range "$rest" [expr "$idx" + 1] end]
     }
   }
+  return "$count"
 }
 
 
@@ -3701,9 +4375,6 @@ proc normalize_isodir_adr {} {
 proc path_touches_isodir {path} {
   global isodir_adr
 
-  # <<<
-  # puts stderr "path_touches_isodir : '$path'" 
-
   normalize_isodir_adr
   set cmp_start 0
   if {"$isodir_adr" == "/"} {
@@ -3718,27 +4389,15 @@ proc path_touches_isodir {path} {
   }
   set l [expr {[string length "$isodir_adr"] - $cmp_start}]
   if {[string length "$path"] < [expr {$l + 2}]} {
-
-    # <<<
-    # puts stderr "path_touches_isodir : shorter than [expr {$l + 2}]" 
-
     return ""
   }
   if {$l > 0} { 
     if {[string range "$path" $cmp_start [expr {$l - 1}]] != \
         [string range "$isodir_adr" $cmp_start end]} {
-
-      # <<<
-      # puts stderr "path_touches_isodir : start does not match" 
-
       return ""
     }
   }
   if {[string range "$path" "$l" "$l"] != "/"} {
-
-    # <<<
-    # puts stderr "path_touches_isodir : start not followed by /" 
-
     return ""
   }
   set subpath [string range "$path" [expr {$l + 1}] end]
@@ -3747,10 +4406,6 @@ proc path_touches_isodir {path} {
     return "$subpath"
   }
   if {"$slash" == 0} {
-
-    # <<<
-    # puts stderr "path_touches_isodir : subpath begins by / : '$subpath'" 
-
     return ""
   }
   return [string range "$subpath" 0 [expr {$slash - 1}]]
@@ -3847,13 +4502,51 @@ proc yell_xorriso_tcltk {} {
   puts stderr "xorriso-tcltk $own_version : Proof of concept for GUI frontends of xorriso\n"
 }
 
- 
+
+# Tells whether an absolute path leads to a directory on hard disk 
+#
+proc localfs_isdir {path} {
+  catch {file lstat "$path" stbuf}
+  if {[info exists stbuf] == 1} {
+    if {$stbuf(type) == "directory"} {return 1}
+  }
+  return 0
+}
+
+
+# Return the list of files of a hard disk filesystem directory
+#
+proc localfs_ls {dir} {
+
+  set result ""
+  if {[localfs_isdir "$dir"] == 0} {return ""}
+  set conn [open "|ls {$dir}" r]
+  while {1} {
+    set ret [gets $conn line]
+    if {"$ret" == -1} {
+  break
+    }
+    set adr [combine_dir_and_name "$dir" "$line"]
+
+    # >>> Obtain all types, not only "d" and "?"
+
+    if {[localfs_isdir "$adr"] == 1} {
+      lappend result "d $line"
+    } else {
+      lappend result "? $line"
+    }
+  }
+  catch {close $conn}
+  return "$result"
+}
+
+
 # -------- start living
 
 
 proc setup_by_args {argv0 argv} {
   global cmd_pipe_adr reply_pipe_adr main_window_geometry click_to_focus
-  global log_file log_conn logging
+  global log_file log_conn logging have_bwidget
   global cmd_conn reply_conn
   global geometry stdout stdin
 
@@ -3921,6 +4614,10 @@ proc setup_by_args {argv0 argv} {
       }
       set logging "1"
     }
+    if {"$opt" == "--no_bwidget"} {
+      set ok "1"
+      set have_bwidget "-1"
+    }
     if {"$ok" == 0} {
       puts stderr "$argv0 : Unknown option '$opt'"
       print_usage "$argv0"
diff --git a/xorriso/xorriso_timestamp.h b/xorriso/xorriso_timestamp.h
index 285899de..8915b6a9 100644
--- a/xorriso/xorriso_timestamp.h
+++ b/xorriso/xorriso_timestamp.h
@@ -1 +1 @@
-#define Xorriso_timestamP "2012.12.30.100913"
+#define Xorriso_timestamP "2012.12.30.115258"