[compiz] Minor fix to multi-head changes for mixed resolutions

[Mike Cook]

Hey, David, for me the recent multihead changes had minor a problem with mixed resolutions (1600x1200 & 1280x1024).  The viewport was getting set partially off screen.

The following tweak fixed it for me:

--- plugins/display.c
+++ plugins/display.c
@@ -2069,7 +2069,7 @@ eventLoop (void)
                    {
                        if (s->nOutputDev > 1)
                            glViewport (s->outputDev[i].region.extents.x1,
-                                       s->outputDev[i].region.extents.y1,
+                                       s->height - s->outputDev[i].region.extents.y2,
                                        s->outputDev[i].width,
                                        s->outputDev[i].height);
 

I still have a problem with cube and rotate in that my primary head works, but the second head is a single flat window which rotates at its center point.  I'll try to look at that next.

Keep up the great work!

...MC