get_device_cursor
Description:
Retrieves a `GdkCursor` pointer for the device currently set on the specified `GdkSurface`.
If the return value is null then there is no custom cursor set on the specified surface, and it is using the cursor for its parent surface.
Use [method@Gdk.Surface.set_cursor] to unset the cursor of the surface.
Parameters:
| this | 
           a `GdkSurface`  | 
      
| device | 
           a pointer `GdkDevice`  | 
      
Returns:
| 
           a `GdkCursor`  |