I’m not entirely certain where the issue lies, so I’ll provide as much system information as I can to assist.
For the last several builds, an issue that disappeared for a few versions, has reared its ugly head again. This being that the dropdown menu for fonts tends to auto-close after selecting a random font. This occurs in both High DPI and normal versions. In order to reliably change text font I’ve grown quite accustomed to using the F4 shortcut as the menu is practically unusable. This may be a problem of my own making, although I don’t seem to have this issue across Microsoft Office, Apache OpenOffice, notepad, textpad, and a suite of other creative tools.
Version of Beta with known issue: All Release Candidates, all betas Feb-May.
This may simply be a problem whereby the number of fonts I have for graphic design purposes overloads the programme and causes some kind of emergency memory dump or something. I don’t know. It’s been a long time since I spent any amount of time coding. While it’s not entirely essential for the purposes Scriviener is intended to serve, it is, nevertheless, a little bit irritating.
I was going to say that I was unable to duplicate this but managed to do so after playing around a bit with how I clicked and moved the mouse on all of the dropdown menus within Scrivener as compared to other programs such as Word, Notepadd++, and some Adobe products. What I noticed on my system using a Dell wireless mouse, was that the tracking speed and click sensitivity varies between the programs. Scrivener, for instance, is fairly sensitive to mouse movements and clicks. Word and Notpad++ not so much. Adobe products varied somewhere in between. Scrivener also has a bit of a delay between the initial click on the dropdown arrow and when the dropdown displays - it is very slight but if you are watching for it, you can see it. With your gamer-style mouse, you probably have the mouse sensitivity and click speed set fairly high (probably by default), while my wireless mouse is set much lower by default. Also, check the click bounce (sensitivity) setting. Some mice/pointing devices can set these settings for individual programs (mine does not, but my daughter’s gaming mouse does) which might be an option for you to get a more consistent mousing experience. FWIW, I have 235 fonts to display which has a tiny bit of a delay in all the programs mentioned when I go to the font picker.
I’m not saying that there isn’t a bug in Scrivener here - they may very well want to adjust some menu display timings - just that there is more than one thing affecting this perceived behavior.