I recently upgraded to a 4K display. I am using Linux Mint and have the 'Monitor scale' set to 200 %. I have a problem with the gambas code editor font being rendered blurry.  The console portion and menus render fine and I can work with blurry icons, but the blurriness on code editor starts to strain my eyes. Any help would be appreciated.

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 Looks like your in front of the rest of us with a 4K monitor!
Looking at the picture I suggest you try a different font. I would change them all to Ubuntu to start with.
You could also look at the Linux Mint forums to see if anybody else has similar issues with 4K.

cogier said

Looking at the picture I suggest you try a different font. I would change them all to Ubuntu to start with.

I already tried both ubuntu and gambas fonts.

Unscii was the third font - A higly pixelated crisp font to better showcase the issue.

On my Linux Mint installation the fonts look crisp elsewhere outside the gambas code editor.

I seem to have no blurriness of the code editor in Solus (a GNU/Linux distribution) where I only have Qt5 and no Gtk (I was unable to find and install all the depencies required for Gtk 2 or 3). In Linux Mint the Gambas IDE seems to use Gtk3 by default, so I wanted to try Gambas with Qt in Linux Mint as well. But I get errors if I launch Gambas using the command: $ env GB_GUI=gb.qt5 gambas3 and same for qt4 as well. Maybe the errors are related to Linux Mint being a stable (i.e. unchanging) distribution with most programs being several years old and perhaps incompatible with the more up to date Gambas (which I have built from source). The errors are present even with display scaling of 100 % as seen on the screenshot below.

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I would appreciate if someone could try  $ env GB_GUI=gb.qt5 gambas3 to confirm the presence or absence of errors on their Linux Mint setup.

PS: I am using Gambas 3.18.2 and Linux Mint 21.2

 have you run the qt5ct settings tool?

there is a font page there, i fixed some problems once by pressing the Create fonts.conf button.

It looks like there is an error in your font config.

Either qt5 font config is not right or it could the theme.  
i would try different themes , some are just a bit buggy.

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BruceSteers said

Have you run the qt5ct settings tool?

Yes, tweaks on the "Fonts"-Tab in "Qt5 Configuration Tool" fixed this and I can now enjoy clear text. Thank you.