[Gambas-bugtracker] Bug #2301: IDE preferences, editor font is a total mess

[bugtracker at gambaswiki.org]

http://gambaswiki.org/bugtracker/edit?object=BUG.2301&from=L21haW4-

Comment #3 by Bruce BRUEN:

Slowly getting closer. It does appear to be a problem in Gambas on Mint 20.1 using the ppa updater only when using the IDE in QT5 mode.

What happens?
If the IDE preferences for Fonts is set in a certain way (Still trying to characterize what this "way" is!) the editor panel uses an incorrect and "corrupted" font. 
In the second screen shot in the original post, you can see one of the effects of the "incorrect fonts". At lines 74 and 78 it looks like there are several spaces between the "If" and the subject - there actually isn't several, there's only one space.
I could list dozens of other examples but they all come down to the same thing.

What I have found out.
1) I thought it was something in "my" configuration. So I created a new plain vanilla user and started using the Gambas IDE there. It worked fine with the default fonts until the next day when I updated the daily ppa. Suddenly, now it happens with that user as well. Note that that user's config files (for gambas3, qt5 and cinnamon) are all unchanged from the defaults when the user was created and first started the Gambas IDE. Some attempts to manually configure the IDE fonts and to configure the Qt5 fonts just made things worse and worse.
2) The effects are not seen in other programs that display text via Qt5.  
3) The effects are not seen in other distros only Mint.