I'm not sure if this is the right place to bring this up, and it's really just a minor issue, but:
On my Windows 10 Home 64-bit system running official MAME v0.187 64-bit, I am experiencing some odd behavior when running '-video opengl' (or bgfx/gdi) and using the Windows 'alt-tab' keys to switch to other windows.
When I run : mame64 pacman -video d3d
I can alt-tab to other windows as expected.
But when I run: 'mame64 pacman -video opengl' (or bgfx/gdi)
'alt-tab' keeps the focus on the MAME window, without switching to the other windows. I have not experienced this behavior with the other (very few, admittedly) opengl applications I have installed on this system.
In case it matters, I have a NVIDIA GeForce GTX 760 (ASUS GTX 760 DirectCU II OC) video adapter, and an Asus ROG Swift PG278Q display (2560 X 1440 @ 144 Hertz), and am running MAME full-screen.
I was wondering if anyone could reproduce this, or if it is just expected behavior, or if there is something going on with my specific setup ?