[Xcb] XCBCopyArea help

[Jeremy A. Kolb]

Okay, I have a window and a nice little pixmap with a black rectangle on 
it.  on my expose event I use XCBCopyArea to copy the drawable (win.p) to 
win.w.  The window is white but the rectangle is black.  so do I use the 
"black" gc that I created (root->black_pixel)? Or white? Neither one seems 
to get anything drawn to the window.  Also, how do I check if an error was 
generated by this function?

Jeremy