Hi,
On computers which have both a mouse/trackpad and a touchscreen, the PopupMenu do not respond correctly to touch events, only the mouse works with them. I have also got reports from users who use a wacom style input device with a pen. It seems that the commit that broke the PopupMenu for touch events is this one:
Before this commit it was workinig fine, but was a bit glitchy when the mouse cursor was positionned under the popupmenu while the user was navigating the menu by touch.