EGL_MESA_screen_surface version 4

[Jim Gettys]

On Thu, 2005-03-24 at 10:25 -0700, Brian Paul wrote:

> Right.  The OpenGL convention is to detect/report errors whenever 
> possible.
> 
> 
> Adam Jackson wrote:
>  > On Wednesday 23 March 2005 20:32, Jon Smirl wrote:
>  >>On Wed, 23 Mar 2005 16:38:34 -0700, Brian Paul
>  >>Did you note somewhere that it is illegal to destroy a surface while
>  >>it is being displayed?
>  >
>  > Why would that be illegal, as opposed to merely undefined?
> 
> OpenGL tries to avoid undefined behaviour whenever possible.  If it's 
> possible to determine that someone's trying to delete a visible 
> surface then there should be a well-defined behavior in that situation.
> 
> Fairly recently the ARB reexamined the case of what exactly happens 
> when a texture object is deleted when the texture is being shared by 
> (and possibly bound in) several rendering contexts.  It's too lengthy 
> to repeat here, but nobody wanted undefined behaviour.

And certainly X has always had that attitude.  X resources (e.g.
pixmaps) are always reference counted, and only actually freed when the
last reference is gone, so that nothing funny happens.  For example, if
you use a pixmap as the background of a window, and then destroy the
pixmap ID, nothing bad happens, and the defined result is that the
pixmap's contents are preserved and used as the background.
			- Jim