Created attachment 13814 [details]
Monodevelop is not properly scaled on HiDpi screen. I have UX303LN laptop with 1920x1080 resolution and 13 inches screen size, running latest KDE and some UI elements are too small. Attached screenshot should describe that more than words. I tried to resolve this problem and when I modify method "Mono.TextEditor.GtkWorkarounds.GetPixelScale()" to return hardcoded value 1.4d, UI looks fine - is properly scaled. Attached screenshot contains on top version with hardcoded pixel scale to 1.4d and underneath original version without my modification.
MonoDevelop -latest from GIT
This isn't something that we can really fix in monodevelop itself. On Mac and Windows we ship our own version of gtk, but on Linux this isn't an option.
If we switch to gtk3 at some point then we'll get support for this from that, but I don't think it's a feature that will ever be backported to gtk2.
I think the original poster shows that this is a bug in monodevelop, as changing the "Mono.TextEditor.GtkWorkarounds.GetPixelScale()" function worked (not anymore, since it's commented out and not used anymore).
This is still an issue and the current code seems to be using gtk3 to determine the scaling factor and in every other gtk3 app this works as expected.