Check for valid framebuffer size before change.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@2531 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/java/src/com/tightvnc/rfbplayer/VncCanvas.java b/java/src/com/tightvnc/rfbplayer/VncCanvas.java
index 3b4a30b..96e8035 100644
--- a/java/src/com/tightvnc/rfbplayer/VncCanvas.java
+++ b/java/src/com/tightvnc/rfbplayer/VncCanvas.java
@@ -249,8 +249,10 @@
             break;
 
           if (rfb.updateRectEncoding == rfb.EncodingNewFBSize) {
-            rfb.setFramebufferSize(rfb.updateRectW, rfb.updateRectH);
-            updateFramebufferSize();
+            if (rfb.updateRectW != 0 && rfb.updateRectH != 0) {
+              rfb.setFramebufferSize(rfb.updateRectW, rfb.updateRectH);
+              updateFramebufferSize();
+            }
             break;
           }