FXCanvas on Win32 HiDPI produces wrong results

Running the attached application produces the following problems:

JDK8:
- If swt.autoscale is on (top-right) the Font-Size is invalid
  and eg. context-menus pop up at the wrong location
- If swt.autoscale is off (top-center) the JavaFX
  embedded scene as it should be and conext menus open at the right
  position

  But this is not an option as other SWT-Areas who use the GC the don't
  renderer appropriately

JDK9:
- If swt.autoscale is on sizes look ok but the embedded scene is blurred
  and eg context-menu is at wrong position and has the wrong font-size

- If swt.autoscale is off (bottom-center) the scene is too small but
  context-menu is at the wrong location

Maybe in a later step we should split up this ticket but I filed it as one for now so that one can see the different problems