I mean context menu opening/closing, combobox/lists opening, info panels opening in dock bar and more.
This is a choice Windows made, and looks IMHO much more clean, polished. My impression with current GNOME action event is that it is very immature, it feels very weird to click and see stuff showing up immediately as soon as I click the mouse instead of waiting for mouse release.
Ex-Windows users will reeeeeeally appreciate, even if they maybe can’t really tell what is off with the current mousedown UX.
This can of course be a config option, defaulted to whatever the GNOME team is more accustomed to/likes more.