Move waiting loop for mapping into Open_Window

Putting it in blit could cause recursive calls:
Resize_Window
  rebcmp_blit
    X_Event_Loop
      Dispatch_Event
        X_Finish_Resizing
          Resize_Window
Flush before waiting for MapNotify
Test fixes for Ubuntu
Allow a routine! to be constructed from a pointer

This is required to wrap openGL extension functions
More function testing in gtk