--- config.def.h
+++ config.def.h
@@ -3,6 +3,7 @@
 /* appearance */
 static const unsigned int borderpx  = 1;        /* border pixel of windows */
 static const unsigned int snap      = 32;       /* snap pixel */
+static const char panel[][20]       = { "xfce4-panel", "Xfce4-panel" }; /* name & cls of panel win */
 static const int showbar            = 1;        /* 0 means no bar */
 static const int topbar             = 1;        /* 0 means bottom bar */
 static const char *fonts[]          = { "monospace:size=10" };