* Both `kdialog` and `gxmessage` are not core components of the KDE or GNOME desktop environments.
* The environment variable `GNOME_DESKTOP_SESSION_ID` has been deprecated for nearly a decade.
* Systems like Steam Deck are shipping with stripped down DEs where these environment variables were set, but without the associated binaries.
The main bulk of this is the new start screen code. To make this work in Raze some more work on the startup procedure is needed.
What this does provide is support for the DOS end-of-game text screens in Duke and SW on non-Windows systems.
Fixes:
* do not strip 'filter' as a directory prefix.
* proper spacing for scaled sheet fonts.
* fix of transparent color in BMF fonts.
* fix restart button on error pane in Windows.
* do not skip over empty 'if's with a condition that would error out.
