This undocumented "private" class was used for various windows UxTheme functions which are available since WinXP. As wxWidgets 3.1 is XP+ it does not make sense anymore to load the theme functions dynamically.
The main/only change in this version is the removal of automatic rules using old Carbon Rez/DeRez/SetFile tools.
This sample shows the use of modern OpenGL (3.2). Closes #16910.