Alternative to bezels for non-MAME emulators

[shroud]

What do you use when you launch from GameEx an emulator that displays a screen smaller than your monitor?

There are so many retro systems with aspect ratio narrower than 16:9 which is the most common for modern monitors. Do you just leave the desktop visible in the background? Do you stretch the emulator aspect ratio to match with that of your monitor? Or have you settled for a better alternative?

[stigzler]

RetroArch allows for the use of inbuilt/custom bezels as far as I'm aware.. You could take a look at that?

Personally, I often go for the stretch and de-pixelate via filters (HQ etc) rather than fidelity to original appearances. 

[shroud]

I don't want to switch to another frontend

[stigzler]

You're welcome. It's not another front end. Think of it as a mid stage emulator launcher. With you..