The offscreen_render_required flag should only be set into the 2 state if it is currently 0, as the 1 state is a full refresh which should maintain precedence. Intel drivers incorrectly clip new graphics buffers  https://tracker.physiomeproject.org/show_bug.cgi?id=2377 Merge from cmgui_2_7_0_plus_fixes revision 8093
The offscreen_render_required flag should only be set into the 2 state if it is currently 0, as the 1 state is a full refresh which should maintain precedence.
Intel drivers incorrectly clip new graphics buffers 
https://tracker.physiomeproject.org/show_bug.cgi?id=2377
Merge from cmgui_2_7_0_plus_fixes revision 8093

cmiss/cmgui,cmiss/cmgui