Avoid extra framebuffer update messages

In most cases we will send an update at the end of processing client
messages so these extra calls only slow things down. Server initiated
events still need an explicit call though.

common/rfb/VNCSConnectionST.cxx

@@ -276,6 +276,7 @@ void VNCSConnectionST::screenLayoutChangeOrClose(rdr::U16 reason)
 {
   try {
     screenLayoutChange(reason);
+    writeFramebufferUpdate();
   } catch(rdr::Exception &e) {
     close(e.str());
   }
@@ -307,6 +308,7 @@ void VNCSConnectionST::setDesktopNameOrClose(const char *name)
 {
   try {
     setDesktopName(name);
+    writeFramebufferUpdate();
   } catch(rdr::Exception& e) {
     close(e.str());
   }
@@ -317,6 +319,7 @@ void VNCSConnectionST::setCursorOrClose()
 {
   try {
     setCursor();
+    writeFramebufferUpdate();
   } catch(rdr::Exception& e) {
     close(e.str());
   }
@@ -327,6 +330,7 @@ void VNCSConnectionST::setLEDStateOrClose(unsigned int state)
 {
   try {
     setLEDState(state);
+    writeFramebufferUpdate();
   } catch(rdr::Exception& e) {
     close(e.str());
   }
@@ -744,7 +748,6 @@ void VNCSConnectionST::setDesktopSize(int fb_width, int fb_height,
   if (!layout.validate(fb_width, fb_height)) {
     writer()->writeExtendedDesktopSize(reasonClient, resultInvalid,
                                        fb_width, fb_height, layout);
-    writeFramebufferUpdate();
     return;
   }
 
@@ -762,10 +765,6 @@ void VNCSConnectionST::setDesktopSize(int fb_width, int fb_height,
         throw Exception("Desktop configured a different screen layout than requested");
     server->notifyScreenLayoutChange(this);
   }
-
-  // but always send back a reply to the requesting client
-  // (do this last as it might throw an exception on socket errors)
-  writeFramebufferUpdate();
 }
 
 void VNCSConnectionST::fence(rdr::U32 flags, unsigned len, const char data[])
@@ -823,7 +822,6 @@ void VNCSConnectionST::enableContinuousUpdates(bool enable,
 
   if (enable) {
     requested.clear();
-    writeFramebufferUpdate();
   } else {
     writer()->writeEndOfContinuousUpdates();
   }
@@ -1243,7 +1241,6 @@ void VNCSConnectionST::screenLayoutChange(rdr::U16 reason)
 
   writer()->writeExtendedDesktopSize(reason, 0, cp.width, cp.height,
                                      cp.screenLayout);
-  writeFramebufferUpdate();
 }
 
 
@@ -1273,8 +1270,6 @@ void VNCSConnectionST::setCursor()
       }
     }
   }
-
-  writeFramebufferUpdate();
 }
 
 void VNCSConnectionST::setDesktopName(const char *name)
@@ -1288,8 +1283,6 @@ void VNCSConnectionST::setDesktopName(const char *name)
     fprintf(stderr, "Client does not support desktop rename\n");
     return;
   }
-
-  writeFramebufferUpdate();
 }
 
 void VNCSConnectionST::setLEDState(unsigned int ledstate)
@@ -1299,12 +1292,7 @@ void VNCSConnectionST::setLEDState(unsigned int ledstate)
 
   cp.setLEDState(ledstate);
 
-  if (!writer()->writeLEDState()) {
-    // No client support
-    return;
-  }
-
-  writeFramebufferUpdate();
+  writer()->writeLEDState();
 }
 
 void VNCSConnectionST::setSocketTimeouts()