In summary: Using Windows to run mGBA on RetroArch yields issues with transparency. Again, I dont know the full technical details of this, but from what Ive seen, Id say this is a pretty good guess.

The 'mgba-qt' package is a Qt frontend with a menu, and should be relatively intuitive. Using the mGBA setting to sync to video does help somewhat, but the improvement is minimal, and its nowhere near as seamless as on Android. Also, the emulator is ported to AmigaOS 4, AROS, GameClub, Wii, webOS, and Zune HD. It is available for Windows, Linux, Mac, BSD, and BeOS. VisualBoy Advance is the most stable Gameboy Advance Emulator and is one of the oldest and well-known Game Boy Emulators. The 'mgba' package contains the command-line version of the emulator, and can be used as `mgba path/to/ROM`. Download mGBA Emulator VisualBoy Advance GBA Emulator. The common understanding is that it's legal to download a ROM only if you own the physical game cartridge (don't quote me on this, IANAL), but you can also find 'homebrew' ROMs which can usually be downloaded and played legally without copyright infringement. Mgba is a Game Boy (classic, Color and Advance) emulator, you need ROM files for such games to try it. I'm also proposing mgba-0.6.0-1.mga6 as a backport candidate for Mageia 6, available in core/backports_testing. Imported in Cauldron as mgba-0.6.0-1.mga7. Finally got to package mGBA, sorry for the delay.

Mgba emulator