Quick tiling double buffereing
The quicktileMode member now is just for the requested tile mode, base the "real" mode only on m_tile.
The requested tile mode is used for double buffering, to look and behave just like requestedMAximizeMode() which is updated immediately, but needs to acknowledge the configure request and render for quickTileMode() (and the right tile() instanced to be associated) to be updated accordingly
Edited by Marco Martin