TODO
  * several vobs per menu
  * set languages for audio files
  * add possibility to remove single audio files from title 
  * buttons: select audio and subtitles, jump cell 1
  * add exit command to title post command drop down list
  * change icon for video + audio titles
  * two lines of text in a button
  * subtitles
  * slideshow
  * show new dialog by first start
  * menu properties: background stretch option, alignment
  * button properties: replace direction "auto" with "auto (buttonX)"
  * colour dialog: store custom colours
  * buttons: default fonts and colours
  * text: background color & alpha channel value
  * select multiply menu objects
  * lock and unlock menu objects
  * SVG backgrounds
  * timeline
  * context menu: play/add movie, assign as background
  * progress dialog: save log
  * fullscreen
  * resume the creation of DVD: add cache for encoded files
  * don't use dnd if it is not available (for wxUniv package)
  * remembering recent projects
  * select the language for different audio streams
  * ability to mux text based subtitles to videos
  * fix menu display (pal: 75x80 dpi, ntsc: 81x72 dpi)
  * menu language property
  * creation of audio DVDs with builtin mp3 converter out of different formats plus mp3 ID tracking editor
  * show progress in the title when minimized
  * start automatically remux if dvdauthor fails with error "SCR moves backwards, remultiplex input"
  * add button "burn again" and "save ISO" to progress dialog (enable after finish)
  * check DVD commands before starting the generation
