FCEUX fullscreen letterboxing

So, I'm trying to get FCEUX play games fullscreen. I've got a 1080p monitor, and I understand that requires that the sides be blank, that's fine. But whenever I go fullscreen, there's also black borders on the top and bottom. There's nothing I can seem to do to get it to scale to the full height of my monitor. In the settings, I've tried changing the fullscreen resolution to 1440x1080 (4:3), but if I switch to fullscreen then, it'll just spit me back out into windowed mode. If I change any of the aspect ratio options, it'll either stretch it to fill the screen, which I obviously don't want, or it won't scale to full height.

I'm using the latest version of FCEUX. Does anybody have any tips for me to get it to play fullscreen properly?

Thanks.

FCEUX probably isn't built to run full screen since it would pixelate a lot of NES games very badly if made to be a large size, hence the reason why there are black bars.
Or it could be broken, which isn't a surprise considering FCE Ultra doesn't have full screen at all, it was a more recent change.

If what cammy said is true, that would be odd. Tho I wouldn't know for that particular emu, i haven't uses NES.

Tho I can say what other emu bahavior Iv encountered incase it applies.

some emu's require a certain resolution, or aspect ratio be enforced for some of the image enhancment filters IF they are enabled... so if u experiement a little and disable all the image enhancments, u may find the fullscreen res behaves differently.

also i dont know if this is unique to zsnes[concerning 2d consoles] or just me but... I find that disabling all image enhancments(except triple buffering) and running it at the lowest possible fullscreen res(keeping proper aspect ratio tho).. the fuzzynes that creates makes it look kind of original, tho u have to lower the brightness or contrast of the LCD cause the original CRTs looked darker, not cause they actually were but because the increased black space between the pixels and low res.

tho I'll add to avoid any confusion, zsnes has the option for image filters to be enabled/disabled at the same time u select the resolution... and selecting the same Res with the enhancment option, but disabling them by clearing the check boxes, does Not produce the same image as if u selected the Res with the "allow image enhancments"=Disabled... it works but is clumsy planning perhaps compared to mame just for example, were u can select whatever resolution u want, and enable 'ddraw' or 'd3d', and then the enahancments for that mode.

If u sit really close to the monitor or have the brightness way up in a bright room, may not work of course unless the emu in question has scanline options for that mode.