When working on a multiple masters file I sometimes wish I could hide the little red triangles that appear in the glyph overview when the masters are not compatible.
It’s like unchecked notifications on your phone. Makes me slightly stressed, looking at my files 
Is it somehow possible to toggle hide/show those?
You can add a custom parameter to your Font Info > Font: Enforce Compatibility Check. Uncheck the box.
This will disable checks whether your masters are compatible, essentially disabling the red triangle. You can re-enable it when you need it.
Hey. Just tried this out, but it’s still showing the red triangles in my glyph overview.
Where did you add the parameter? Did you uncheck the box?
Edit: Just tried myself, the red warning still shows. Is this a new bug? (I never use this functionality)
I added the parameter under “Font info” → “Font” and yes I unchecked the Box on the right side.
Yeah I don’t know if it’s a new bug either. Haven’t used the functionality before.
The “Enforce Compatibility Check” between the behavior of Glyphs 2 and 3. In G2, it would only complain if there is an instance between two masters. Otherwise, e.g. if you have instance only at the same places as your masters, it would not complain. Glyphs 3 always checks all masters by default because it assumes you intend to export as a variable font.
Alright, but isn’t the custom parameter supposed to also disable the compatibility checks if you uncheck the box? This doesn’t work.
No. It basically switches back to the way it worked in Glyphs 2 as I explained above. What you mean would be “Disable Compatibility Check”.
To get rid of the red marks you need to disable or remove all interpolating instances.
that’s a pity, as sometimes when we are making things we love we might decide not to export a variable font, and prefer to not be distracted by red bars. why not remove the option to unenforce compatibility check?
That would be a different use case.
If you do not plan to interpolate, why do you have instances between those masters? If you don’t have interpolating instances, you don’t get red triangles.
I have an icon font with masters for legacy and revision in one file for instance
there is no goal to have them compatible at any point
the triangles are a stressor to see and add visual noise in the overview. Isn’t this a user preference like show background or anything like that and should be possible to toggle?
Yes. There is a custom parameter called Enforce Compatibility Check. Add it to Font Info > Font, turn the left checkbox on (activates the parameter), turn the right checkbox off (tells it to not check for compatibility).
Yes as it was mentioned above I followed the steps.
and as described by other users this didn’t show the expected behaviour.
And didn’t instantly for me either for some reason. but I see now it’s gone.
Adding the parameter doesn’t recalculate the compatibility right away. You need to change anything on the glyphs to trigger a recalculation.