Re: [gtk-list] Re: GraphicsExpose (was Re: About the About Box)

[Raph Levien <raph acm org>]

On Sun, 14 Dec 1997, Owen Taylor wrote:

> After the XCopyArea call, X thinks that the entire window now contains
> valid information (for the purpose of calculating GraphicsExpose
> events). But actually, that isn't true until the GraphicsExpose events
> filter through the queue. Before then, X has blanked out the improper
> areas to the background color (*) If another motion event occurs
> before then, X will copy the blanked out areas, but not produce
> graphics expose events for them, thus leading to the observed gray
> bars. 

I had another thought on this and wanted to throw it out there. Since 
this is at heart a race condition caused by asynchronous GraphicsExpose 
events following XCopyArea, wouldn't the problem be fixed by doing an 
XSync right before the scroll? I can't imagine the performance 
degradation would be that serious, and it sounds a whole lot simpler 
than some of the other proposals.

Raph