Fullscreen mode not true fullscreen

[oscarproud]

Confusing title but I'm on Kubuntu 18.04 and when I went to fullscreen on a video, I saw a vertical line on the right side of my screen maybe 1 pixel wide with different colors along its length; when I minimized my screen, I saw that it was basically my wallpaper "bleeding" through. I confirmed this by switching my wallpaper to a solid black color and now it's all black in that area. It's not just my wallpaper, it can be any window including my internet browser that SMplayer fails to cover. Is there a setting I need to change or do I just have to use a black wallpaper when playing videos?

Thanks

EDIT: https://imgur.com/a/U4gWRhb
Shows what I mean. The top is my wallpaper and on the bottom is a video running in fullscreen mode, you can see the green from the wallpaper on the right border edge

[rvm]

I never had this problem.

Does it happen as well if you select a different video output in preferences -> general?

[oscarproud]

Yeah I tried changing the video outputs and no dice.

I use my TV monitor as my computer screen with a wireless keyboard + mouse and sit some distance away; I have generally always scaled up my display in Windows so I can see from further away but it seems that it doesn't play nice in Kubuntu. Resetting the scale back to the lowest setting seems to have "fixed" that problem but of course now it's a bit uncomfortable to use for general browsing and navigating so back to Windows I go. Thanks.