Remote functionalities are:

• send mouse and keyboard input (if interactive mode is active)
• fit the gui to the screen (only if main window has no focus)
• change the frame latency

OpenGL implementation only:

• if nullptr is passed to the initgui function no window is created
• if context is null it is assumed that no window exists
• the backend only updates the mouse position if the window is focused (to prevent override of remote control)