[Xcb] XCB documentation effort

[Michael Stapelberg]

Hi Uli,

Excerpts from Uli Schlachter's message of 2011-11-23 09:06:52 +0000:
> cairo's xcb backend does use xcb_put_image_request_t together with 
> xcb_send_request() to send part of an image to the X server without having to 
> copy the part into a continous memory chunk:
> 
> http://cgit.freedesktop.org/cairo/tree/src/cairo-xcb-connection-core.c#n162
> 
> I don't say the request structs have to be documented (but xcb_send_request() 
> really could mention that it wants vec[-1] and vec[-2]), just that there is a 
> (single, weird) use for them out there.
Thanks for the explanation. It makes sense to expose the structs, then :).

Best regards,
Michael