Continuing the discussion from Running QubesOS in QubesOS:
open the menubar, hit [PrtScn] key
If that didn’t work, go to Settings | Keyboard | Application Shortcuts and make sure
xfce4-screenshooter -f is assigned to the
Taking a screenshot is possible, it’s just the hotkey that’s dysfunctional because the menu is already grabbing the keyboard while it is open. You could instead queue up a delayed screenshot (e.g. System Tools → Screenshot → Delay before capturing) and then open the menu.
Pasting here from the other thread:
the hotkey that’s dysfunctional because the menu is already grabbing the keyboard while it is open
I’ve also noticed that this blocks the screen from locking as well.
For example, I have my screen lock when my laptop lid is closed, but a few times per year I realize when I come back to an unattended computer with the laptop lid closed, the screen is not locked because the application menu was open. I’ve been meaning to create a bug report about this for a while.
Do you know what exactly is the root cause of some actions (like printscreen and lockscreen) being blocked when the application menu is open?
The application menu and similar windows without a title bar (“override redirect” windows that aren’t managed by the window manager) are usually calling
XGrabKeyboard() to allow navigation with arrow keys etc. When the lock screen attempts to grab the keyboard too it fails (because only one X11 client can do it at a time) and quits.
As for hotkey listeners calling
XGrabKey(), IIUC those just get preempted by anything else grabbing the whole keyboard.
Unfortunately this is a classic X11 nuisance that’s not easily fixable, unless it’s by switching to a text console based lock screen such as
physlock, or eventually migrating from X11 to Wayland.