Releasing mouse pointer in virt-manager on macOs
If you are using virt-manager on macOs with XQuartz you might know the problem to release the mouse once you have entered a virtual machine. You can solve this issue by creating an additional file in your profile directory ~/.Xmodmap. This file must contain the necessary keyboard mappings to be able to release the mouse pointer.
keycode 66 = Alt_L
keycode 69 = Alt_R
add Mod1 = Alt_L
add Mod1 = Alt_R
Save the file and execute chmod 700 .Xmodmap . Than restart XQuartz and open virt-manager again. Using your left Control and left Option key will now release the mousepointer.