updated for version 7.3.591
Problem:    Can only move to a tab by absolute number.
Solution:   Move a number of tabs to the left or the right. (Lech Lorens)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 6740a51..cc80c14 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -7478,7 +7478,42 @@
 ex_tabmove(eap)
     exarg_T	*eap;
 {
-    tabpage_move(eap->addr_count == 0 ? 9999 : (int)eap->line2);
+    int tab_number = 9999;
+
+    if (eap->arg && *eap->arg != NUL)
+    {
+	char_u *p = eap->arg;
+	int    relative = 0; /* argument +N/-N means: move N places to the
+			      * right/left relative to the current position. */
+
+	if (*eap->arg == '-')
+	{
+	    relative = -1;
+	    p = eap->arg + 1;
+	}
+	else if (*eap->arg == '+')
+	{
+	    relative = 1;
+	    p = eap->arg + 1;
+	}
+	else
+	    p = eap->arg;
+
+	if (p == skipdigits(p))
+	{
+	    /* No numbers as argument. */
+	    eap->errmsg = e_invarg;
+	    return;
+	}
+
+	tab_number = getdigits(&p);
+	if (relative != 0)
+	    tab_number = tab_number * relative + tabpage_index(curtab) - 1;;
+    }
+    else if (eap->addr_count != 0)
+	tab_number = eap->line2;
+
+    tabpage_move(tab_number);
 }
 
 /*