With Qt 5.14 and earlier, it was possible to open a menu and activate a menu item in a single action:

1. Press left mouse button on menu title and hold the button
2. Drag the pointer to the desired menu item
3. Release the left mouse button

With Qt 5.15, the menu item no longer activates. The mouse button release event appears to be ignored and the menu remains open.

I hope this behavior change was not intentional. It makes Qt inconsistent with the way both MS Windows and GTK menus work, and breaks decades of muscle memory for me.

Other reports of the issue:

https://bbs.archlinux.org/viewtopic.php?id=256448
https://forum.kde.org/viewtopic.php?f=289&t=161733#p433517