Prevent rendering uninitialized Pixmap contents on X11
The Pixmap is filled in as updates from the server arrive. Before the first full update, it would contain undefined contents, which would be rendered onto the ViewPort.
Clearing the Pixmap is only done on startup and when changing the server resolution, so it's not performance critical.
diff --git a/vncviewer/PlatformPixelBuffer.cxx b/vncviewer/PlatformPixelBuffer.cxx
index e6a054a..be6f704 100644
--- a/vncviewer/PlatformPixelBuffer.cxx
+++ b/vncviewer/PlatformPixelBuffer.cxx
@@ -58,6 +58,9 @@
data = (rdr::U8*)xim->data;
stride = xim->bytes_per_line / (getPF().bpp/8);
+
+ // On X11, the Pixmap backing this Surface is uninitialized.
+ clear(0, 0, 0);
#else
FullFramePixelBuffer::data = (rdr::U8*)Surface::data;
stride = width;