Problem
If you want to increase the display resolution of a Linux guest system, one of the following error messages appears:
GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._gnome_2drr_2derror_2dquark.Code2:could not set the configuration for CRTC 63
[drm:drm_crtc_helper_set_config [drm_kms_helper]] *ERROR* failed to set mode on [CRTC:29:crtc-0]
(Possible) Solution
Allocate more video memory to the guest system in the VirtualBox settings.
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