The behavior is observed when running brave-browser on TCL12 x86_64 or TCL11.1 x86_64 with Xorg (Xvesa doesn't work with my hardware, so I can't test it). Other tested browsers (e.g., firefox, chromium) do not have this problem. The same exact brave-browser binary running on a different OS (e.g., Devuan) on this same machine does not have this problem.
A quick and easy way to reproduce:
1. Load brave-browser.tcz
2. Start the browser and go to
http://forum.tinycorelinux.net3. Login to the forum
4. Hover over "My Messages" to activate the popup menu
5. Click on "Read your messages"
6. The menu disappears without taking you to messages section

I've noticed the problem on multiple websites, so it is not a problem with the TCL forum site.
All the relevant software (Xorg, gtk3, the browser itself) is so complex that I'm at a loss how to even start troubleshooting this. Any ideas?