diff -Naur dockapps.orig/xutils.c dockapps/xutils.c
--- dockapps.orig/xutils.c	2014-12-09 20:31:13.000000000 +0100
+++ dockapps/xutils.c	2020-03-29 13:29:01.027698381 +0200
@@ -54,6 +54,11 @@
 XpmIcon		wmgen;
 Pixmap		pixmask;
 
+Display		*display;
+Window          Root;
+Window          iconwin, win;
+int             screen;
+int             DisplayDepth;
 
 
 
diff -Naur dockapps.orig/xutils.h dockapps/xutils.h
--- dockapps.orig/xutils.h	2014-12-09 20:31:13.000000000 +0100
+++ dockapps/xutils.h	2020-03-29 13:29:10.728695410 +0200
@@ -18,11 +18,11 @@
 /*
  *   Global variable
  */
-Display		*display;
-Window          Root;
-Window          iconwin, win;
-int             screen;
-int             DisplayDepth;
+extern Display		*display;
+extern Window          Root;
+extern Window          iconwin, win;
+extern int             screen;
+extern int             DisplayDepth;