That makes it easier to use partial screens, while using automatic alignment.
Default is still automatic resizing as before, thought it got changed a bit as it looked a bit strange.
Before it only set the lower-right corner, but compared to driver screensizes, so it behaved a bit strange
when the leftTop corner of the rootGuiElement was changed (different than when the rightBottom corner was set).
Could be the idea before was that only clipping matters.
git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6163 dfc29bdd-3216-0410-991c-e03cc46cb475