I think on_release has better UX. More importantly, on desktop linux with kivy 2.0.0rc2, on_press does not work for me. (but on Android, with kivy 1.11.1, it does)
I think on_release has better UX. More importantly, on desktop linux with kivy 2.0.0rc2, on_press does not work for me. (but on Android, with kivy 1.11.1, it does)