File open dialog doesn't show lowercase .tpx files on GTK2/Linux

[krystophny]

Only files with uppercase .TpX extensions are treated by the open dialog on Linux. According to https://forum.lazarus.freepascal.org/index.php?topic=22074.0 the correct way to handle this would be

OpenDialog1.Filter :=
  {$ifdef LCLGtk2}
    '*.txt|*.[Tt][Xx][Tt]'; // Gtk2
  {$else}
    '*.txt|*.txt'; // win32/64 and Qt4
  {$endif}

For the save dialog in the future only lowercase .tpx extensions will be allowed to be consistent.

[krystophny]

This is now fixed in 8bddd5e for v1.6. For picture files there is still a TODO in the code to make all extensions case-insensitive. Currently only lowercase extensions work on Linux/GTK2 for png, jpg etc.