Change resolution of Lubuntu login screen

I have Lubuntu installed in a VirtualBox. The login screen (and Lubuntu splash screen) defaulted to 640x480 resolution. The resolution of the Lubuntu desktop is 1680x1050, which is the largest resolution I could use in a VirtualBox without losing the LXQt Panel.

Is there a way of changing the resolution of the login screen to the same 1680x1050? I looked at the manual page for SDDM Configuration and this is not covered.

Thanks in advance.

I don’t think this is a Lubuntu specific thing. I personally made the case in the forum for Virtualbox about some 2 years ago now but that didn’t lead me to anything… I’ve reinstalled Virtualbox so many times—each time reviewing everything I did—but to this day I still get this on any VM I run now (be it Windows, Linux, etc.).

Apparently not enough people had the issue I had at the time to warrant a bug so I have no clue if that ever got recorded somewhere other than my lousy post.

If you’re not able to get full-screen after logging in despite putting Virtualbox in full screen mode, my guess would be to make sure you have Guest Additions installed in the VM.


Using VirtualBox, the maximum screen resolution I can get (in full-screen mode) is 1680x1050 on the desktop, so this is fine.

It’s the resolution for the SDDM login screen that I need to enlarge.

I think that this upstream issue may have something to do with it:

tl;dr SDDM does some automagic reading of information from displays and it’s sometimes wrong. This is likely a combination of a problem with VirtualBox and underlying Qt libraries.

Unfortunately, I see no solution in sight.

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