The little grabby handle in the corner of an area. Now uses 1 draw call
instead of 6.
Also one version of the (+) icon to show a hidden region. Why do we
have multiple versions of this?
Fixed a harmless signed/unsigned error.
Fixed a GL state error that prematurely disabled blending.
Added imm_draw_filled_circle function, which can be used for drawing
other widgets.
Work toward T49042 and T49043