return location for the X coordinate of the device location, relative to the window origin, or %NULL.
return location for the Y coordinate of the device location, relative to the window origin, or %NULL.
the #GdkWindow under the device position, or %NULL.
3.0
Obtains the window underneath @device, returning the location of the device in @win_x and @win_y. Returns %NULL if the window tree under @device is not known to GDK (for example, belongs to another application).
As a slave device coordinates are those of its master pointer, This function may not be called on devices of type %GDK_DEVICE_TYPE_SLAVE, unless there is an ongoing grab on them, see gdk_device_grab().