Clear the window to rather light grey when switching to RGB mode.
diff --git a/Demo/sgi/video/VFile.py b/Demo/sgi/video/VFile.py
index d63911b..17f677f 100755
--- a/Demo/sgi/video/VFile.py
+++ b/Demo/sgi/video/VFile.py
@@ -301,6 +301,8 @@
 		if self.format == 'rgb':
 			gl.RGBmode()
 			gl.gconfig()
+			gl.RGBcolor(200, 200, 200)
+			gl.clear()
 			return
 		gl.cmode()
 		gl.gconfig()