The GEDKeeper program has a function for switching between interface themes. This is done in the "Tools\Themes" menu, and switching occurs immediately, without restarting the program.
At the moment, the following themes are implemented in the program:
Themes support changing the color of the main elements of the program design, the font type and size, as well as menu glyphs/icons.
Any user of the program can copy a file of any theme in the themes folder in the program installation location, give the file their own name, change the theme name in the file itself and customize the colors as they like. There is no visual editor in the program itself for this, and probably will not be. A certain set of skills is required to change themes at your own discretion. Users can send their theme files. Sufficiently harmonious and interesting ones can be included in the program package with the author's name recorded in the program development history.
Note: GK v3.xx series of versions is based on a cross-platform framework, which limits the ability to change the colors of toolbars, menus, tabbed components and some others.