Can't move window with HdyHeaderbar
If you use python and libhandy and you adding to a HdyWindow or HdyApplicationWindow a HdyHeaderBar (or HdyWindowHandle) than you can't move the window.
Here is an example. Clone this with Builder.
I tested it on Fedora 32 Workstation in a newly created VM and on Manjaro. They were too using the Gnome Desktop.
But all other functions that a Window Headerbar offer works. For example the right click menu. I can only move the window if I am using the Super-Key.
Here is also a article on Headerbars and Windows from libhandy