Added new exception rfb::UnsupportedPixelFormatException.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@598 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/rfb/ScaledPixelBuffer.cxx b/common/rfb/ScaledPixelBuffer.cxx
index 5892a97..e459b39 100644
--- a/common/rfb/ScaledPixelBuffer.cxx
+++ b/common/rfb/ScaledPixelBuffer.cxx
@@ -51,9 +51,7 @@
 }
 
 void ScaledPixelBuffer::setPF(const PixelFormat &pf_) {
-  if (pf_.depth != 24) {
-    throw rfb::Exception("rfb::ScaledPixelBuffer support only the true colour pixel format.");
-  }
+  if (pf_.depth != 24) throw rfb::UnsupportedPixelFormatException();
   pf = pf_;
 }