Set the class hints for managed windows.

diff --git a/tsx11/X11_calls b/tsx11/X11_calls
index 78fd27b..96350b0 100644
--- a/tsx11/X11_calls
+++ b/tsx11/X11_calls
@@ -113,6 +113,7 @@
 XSendEvent
 XSetArcMode
 XSetBackground
+XSetClassHint
 XSetClipMask
 XSetClipOrigin
 XSetClipRectangles