Explicitly check screen layout after change

There are some cases where the server state will not automatically
be updated on a change. A prominent one is when only RFB attributes
were changes (e.g. the screen ID) but nothing else. In that case
there is no actual change in the X server, so it never sends any
notification about change back to us.

unix/x0vncserver/XDesktop.cxx

@@ -567,11 +567,14 @@ unsigned int XDesktop::setScreenLayout(int fb_width, int fb_height,
      VNCSConnectionST::setDesktopSize. Another ExtendedDesktopSize
      with reason=0 will be sent in response to the changes seen by the
      event handler. */
-  if (adjustedLayout != layout) {
+  if (adjustedLayout != layout)
     return rfb::resultInvalid;
-  } else {
-    return ret;
-  }
+
+  // Explicitly update the server state with the result as there
+  // can be corner cases where we don't get feedback from the X server
+  server->setScreenLayout(computeScreenLayout());
+
+  return ret;
 
 #else
   return rfb::resultProhibited;

unix/xserver/hw/vnc/XserverDesktop.cc

@@ -557,6 +557,8 @@ void XserverDesktop::clientCutText(const char* str, int len)
 unsigned int XserverDesktop::setScreenLayout(int fb_width, int fb_height,
                                              const rfb::ScreenSet& layout)
 {
+  unsigned int result;
+
   char buffer[2048];
   vlog.debug("Got request for framebuffer resize to %dx%d",
              fb_width, fb_height);
@@ -564,7 +566,13 @@ unsigned int XserverDesktop::setScreenLayout(int fb_width, int fb_height,
   vlog.debug("%s", buffer);
 
   vncSetGlueContext(screenIndex);
-  return ::setScreenLayout(fb_width, fb_height, layout, &outputIdMap);
+  result = ::setScreenLayout(fb_width, fb_height, layout, &outputIdMap);
+
+  // Explicitly update the server state with the result as there
+  // can be corner cases where we don't get feedback from the X core
+  refreshScreenLayout();
+
+  return result;
 }
 
 void XserverDesktop::grabRegion(const rfb::Region& region)