Simple window without any functionality:
GuiParas equ "Test", w300, h200, bBlueGreen
include \masm32\MasmBasic\Res\MbGui.asm
GuiEnd
With MASM 8.0 ... 15.0, I get this:
MASM : fatal error A1016: Internal error
Version 8.00.50727.104
ExceptionCode = C0000005
Assembles fine with MASM 6.15 and the latest UAsm, AsmC and JWasm versions. In case you absolutely need to use MASM: inserting a blank for the background para helps: b BlueGreen works.
Note only certain colours are affected, like Turquoise and BlueGreen. Red, Green, Blue, Yellow work. Even bRgbCol(80, 255, 255) works just fine.