On 7/18/11 10:50 AM, Daniel Colascione wrote:
> If it works, /dev/windows would allow us to get rid of not only the self-pipe
> and the clipboard thread, but the UI thread as well, though it'd be easier to
> keep the last of these for compatibility for the NT build.

Actually, I spoke too soon regarding the clipboard thread: the problem is that
when we receive a WM_RENDERFORMAT message, we have to call SetClipboardData
_before we return from the window procedure_.  This requirement is incompatible
with using lisp code to render clipboard content: we might have received a
window message at an inopportune time for calling back into Lisp, and we can't
delay the response to WM_RENDERFORMAT by re-queuing or somesuch.  Today's NT
clipboard code doesn't have to address the issue because it never calls into Lisp.

We can address this problem by using a separate message loop for the clipboard;
that way, the clipboard windowproc can wait as long as it wants to reply to
WM_RENDERFORMAT while the main thread does its thing and eventually gets around
to calling our queued timer.  I think this approach (which my patch implements)
is ultimately the right one.