diff -urp dwm-6.1/dwm.c dwm-6.1-patched/dwm.c
--- dwm-6.1/dwm.c	2015-11-09 06:39:37.000000000 +0800
+++ dwm-6.1-patched/dwm.c	2016-03-24 23:56:35.435047948 +0800
@@ -206,6 +206,7 @@ static void setup(void);
 static void showhide(Client *c);
 static void sigchld(int unused);
 static void spawn(const Arg *arg);
+static void switchcol(const Arg *arg);
 static void tag(const Arg *arg);
 static void tagmon(const Arg *arg);
 static void tile(Monitor *);
@@ -1645,6 +1646,35 @@ spawn(const Arg *arg)
 	}
 }
 
+void
+switchcol(const Arg *arg)
+{
+	Client *c, *t;
+	int col = 0;
+	int i;
+
+	if (!selmon->sel)
+		return;
+	for (i = 0, c = nexttiled(selmon->clients); c ;
+	     c = nexttiled(c->next), i++) {
+		if (c == selmon->sel)
+			col = (i + 1) > selmon->nmaster;
+	}
+	if (i <= selmon->nmaster)
+		return;
+	for (c = selmon->stack; c; c = c->snext) {
+		if (!ISVISIBLE(c))
+			continue;
+		for (i = 0, t = nexttiled(selmon->clients); t && t != c;
+		     t = nexttiled(t->next), i++);
+		if (t && (i + 1 > selmon->nmaster) != col) {
+			focus(c);
+			restack(selmon);
+			break;
+		}
+	}
+}
+
 void
 tag(const Arg *arg)
 {