Sm3 shows a 4:3 image but it's drawn in a 16:9 window

[hamburglin]

So, this is a problem specifically effecting gun4ir light guns in both supermodel3 and flycast. Other light guns may be affected but I'm not sure. Similar emulators that don't have this problem are MAME and sega model 2 emulator.

The problem:
Pointing the lightgun at the center of the screen is accurate, but the farther you move to the left or right side of the screen (not top or bottom), the crosshairs move too far towards that edge. Imagine pointing about 3 inches away from the edge of the screen. The gun cursor will incorrectly be at the very edge of the screen. Just as a reminder, these light guns operate like mouses, and off of x/y coordinates.

The cause (I think):
The game video is shown in a 4:3 screen (please ignore the widescreen option), but the actual game screen/window is in 16:9. It is NOT a 4:3 screen that happens to have borders added around it (like MAME and super model 2). Why does this matter? Because the emulator is feeding incorrect mouse coordinates. It's feeding 16:9 worth of coordinates instead of 4:3 worth of coordinates. This is why the gun cursors are "stretched" when you start pointing towards the edge of the screen. Just like a 4:3 image that is stretch to 16:9 would do.

Gun4ir evidence:
Gun4ir allows you to set if you're pointing at a 4:3 image, or a widecreen 16:9 image. If it's set to 4:3, this problem occurs. If it's set to 16:9 (even though the game is still 4:3!!!) the problem is fixed. So why not set the guns to this? Because it's a pain in the a** to reconfigure it before each game, especially when running a custom arcade cabinet that isn't supposed to be accessing Windows.

So yeah, I'm also positive I understand why the issue is occurring but I have no way to no for sure. If it's not the video itself, then MAME and sea model 2 must be doing some extra mouse 4:3 restrictions or something when on a 16:9 window. It would be nice to know if this is fixable or not. I have a feeling it would be a tough fix due to it being a core part of the video engine. However, maybe there is a simpler setting to change due to how MAME and supermodel 2 are handling this correctly.