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In any DRAWTYPE_CAIRO mode, we now do all our Cairo drawing to a Cairo image surface which lives on the client; then we either blit directly from that to the window (if we're in GTK3 mode, or GTK2 without deprecated pieces of API), or else we blit from the Cairo surface to the server-side pixmap and then from there to the actual window. In DRAWTYPE_GDK mode, nothing much has changed: we still draw directly to the server-side pixmap using the GDK drawing API, then blit from there to the window. But there is one change, namely that the blit is no longer done proactively - instead, we queue a redraw of the affected rectangle, and wait until we're called back by the expose handler. The main aim of all this is to arrange that the only time we ever draw to the real window is in response to expose/draw events. The experimental GTK3 OS X port stopped working a week or two ago (I presume in response to an OS update) with the symptoms that attempts to draw on the window outside the context of a "draw" event handler just didn't seem to work any more; this change fixes it. In addition to that benefit, this change also has obvious performance advantages in principle. No more expensive text rendering in response to an expose event - just re-copy to the window from the bitmap we already have, from wherever it's stored that's nearest. Moreover, this seems to have fixed the significant performance problem with X server-side fonts under GTK. I didn't expect _that_! I'd guessed that the approach of downloading character bitmaps and rendering them manually via Cairo was just inherently slow for some reason. I've no real idea _why_ this change improves matters so much; my best guess is that perhaps there's an overhead in each drawing operation to a GDK Cairo surface, so we win by doing lots of operations to a much faster image surface and then batching them up into one GDK Cairo operation. But whyever it is, I'm certainly not complaining! (In fact, it now seems to be noticeably _faster_, at least on my usual local X displays, to draw server-side fonts using that technique than using the old GDK approach. I may yet decide to switch over...)