MarkDirty: invalidate the entire window.

invalidateForControl is not good enough
Revert "MarkDirty: invalidate the entire window."

This reverts commit 165d72a97cf3caf5c85bbb9b0daf2b0915d46500.
Scrollbar: HasBackground needs to consider the slider being wider than the background.
partially revert 26a92b1
Use FONTDLG for GemRB version string label

  * EXOFONT does not have lowercase letters
CanSee: nonactors ignore LOS, at least in pst

fixes a problem with one of the doors in the Alley of lingering sighs
Make sure to append _DEAD to the actor name when checking kaputz for deadness