It's also difficult because what is the native behavior here? On Windows the different official Microsoft UI toolkits behave differently. For example the latest

It's also difficult because what is the native behavior here? On Windows the different official Microsoft UI toolkits behave differently. For example the latest Windows 11 UI stuff works like egui in that it opens the dropdown on release, while older GDI stuff opens the dropdown on press, but won't let you make a choice until you release.