Correctly handle screen layout with offset

We miscalculated the screen layout if the geometry had an offset as we
adjusted the real screen layout to account for the offset, but compared
it to the unadjusted geometry.

unix/x0vncserver/XDesktop.cxx

@@ -422,6 +422,7 @@ void XDesktop::clientCutText(const char* str) {
 ScreenSet XDesktop::computeScreenLayout()
 {
   ScreenSet layout;
+  char buffer[2048];
 
 #ifdef HAVE_XRANDR
   XRRScreenResources *res = XRRGetScreenResources(dpy, DefaultRootWindow(dpy));
@@ -439,13 +440,11 @@ ScreenSet XDesktop::computeScreenLayout()
   Point offset(-geometry->offsetLeft(), -geometry->offsetTop());
   for (iter = layout.begin();iter != layout.end();iter = iter_next) {
     iter_next = iter; ++iter_next;
-    iter->dimensions = iter->dimensions.translate(offset);
-    if (iter->dimensions.enclosed_by(geometry->getRect()))
-        continue;
     iter->dimensions = iter->dimensions.intersect(geometry->getRect());
-    if (iter->dimensions.is_empty()) {
+    if (iter->dimensions.is_empty())
       layout.remove_screen(iter->id);
-    }
+    else
+      iter->dimensions = iter->dimensions.translate(offset);
   }
 #endif
 
@@ -454,6 +453,10 @@ ScreenSet XDesktop::computeScreenLayout()
     layout.add_screen(rfb::Screen(0, 0, 0, geometry->width(),
                                   geometry->height(), 0));
 
+  vlog.debug("Detected screen layout:");
+  layout.print(buffer, sizeof(buffer));
+  vlog.debug("%s", buffer);
+
   return layout;
 }