I just moved over to Linux Mint 20.3 Cinnamon (from decades of Windows) and installed MAME using the Synaptic Package Manager, which gave me version 0.220. I know there's a more recent version (and that may be the solution,) but this is where I am now. I can easily run MAME just fine on the desktop LCD, but I think it would just about rule if I could get it to output to both at the same time so I can just look at whichever display I want to right at that moment. I want to run in full screen if possible. The desktop LCD is 1920*1080, and the projector *tells Linux* (and Windows before that) that it's also 1080p, but it seems to actually be showing 1280*720 - everything is much larger relative to the desktop on the projector, like my icons and thumbnails and so on.
It looks like I should just be going to Configure Options > Video Options > Number of Screens > 2 . When I do that, the projector goes black and the LCD just shows the standard desktop like MAME isn't running. Although it defaults to opengl, I've tried each of the video modes with the same results. If I run MAME in windowed mode and drag the window over to the projector, when I choose a game the window pops back over to the LCD, but of course still in a window. If I Alt-Tab to get the mouse back I can drag The MAME window over to the projector and play there, but the window is large enough that I can't see the whole thing - the bottom is cut off, even in windowed mode.
I guess if I really had to, I would like to choose which display to use full time - like set the projector as my main display for MAME. Then I could play games with an 8 foot screen. :D I can already run MAME on the desktop LCD only, so that's not really an improvement. I guess if it's really necessary I might could just set both displays to 720p, but I really like all that real estate on the desktop full time.
Is there a way to do what I want? It looks like it's *supposed* to be possible, but maybe I'm just not doing it right. Or possibly that was fixed in a newer version and I just need to upgrade. I do have the debian file of 0.241 - should I just uninstall what I have and try that one first?
Thank you so much for your time and attention. I know it's just old video games, but for a half-century old man, what I want would be pretty dang sweet. :D