ecere/gui/drivers/XInterface: (#850) Fixed re-maximized window position confusion
- The problem would occur on Unity after unmaximizing, moving, then maximizing a window,
  mouse events would then be reported at the wrong location.
- This was caused by great convolution regarding the 'x' and 'y' members of XConfigureEvents having a
  different meaning depending on the value of 'send_event', which the X11 books, tronche.com API reference
  as well as the man pages said nothing about. Found out the hard way that, as the ICCCM puts it in section 4.1.5
  "The general rule is that coordinates in real ConfigureNotify events are in the parent's space;
  in synthetic events, they are in the root space."
- Had previous suspected something like this, as the bool 'offset' variable left in the code shows, but had not fully
  understood what was going on (understandably, givin how non-sensical this design decision was
  and the conflicting and all split up documentation).