WindowState are not properly in sync between the VM and the XCB lighthouse backend.

If you open the attached example, maximize the window before 9s, and then wait the timer to fire up, you will see in the terminal that the window state showed is 0 -> WindowNoState despite the window has been maximized. My investigation shows that there is actually no code to handle the window state change from the VM in the XCB backend. XCP_PROPERTY_NOTIFY need to be properly parsed to handle this case.