Prevents calling ActivateContext while holding gl lock, e.g. when preloading 
texture in sampler().

biSizeImage has an extra line added to it, and passing it to memcpy can cause a 
crash.

All XIM interaction will soon pass through this functionality instead
of directly to imm32.

gdi32: Move negative lfWidth test into a separate body, skip the test if there is no 'x' in the font.