diff -Naur dwm-6.1/config.def.h dwm-6.1-patched/config.def.h
--- dwm-6.1/config.def.h	2015-12-29 21:11:08.256735537 +0800
+++ dwm-6.1-patched/config.def.h	2015-12-29 21:08:01.453396528 +0800
@@ -15,6 +15,8 @@
 static const unsigned int snap      = 32;       /* snap pixel */
 static const int showbar            = 1;        /* 0 means no bar */
 static const int topbar             = 1;        /* 0 means bottom bar */
+static const char normmarkcolor[]   = "#775500";
+static const char selmarkcolor[]    = "#775577";
 
 /* tagging */
 static const char *tags[] = { "1", "2", "3", "4", "5", "6", "7", "8", "9" };
@@ -59,6 +61,7 @@
 
 static Key keys[] = {
 	/* modifier                     key        function        argument */
+	{ MODKEY,                       XK_semicolon, setmark,     {.i = 1 } },
 	{ MODKEY,                       XK_p,      spawn,          {.v = dmenucmd } },
 	{ MODKEY|ShiftMask,             XK_Return, spawn,          {.v = termcmd } },
 	{ MODKEY,                       XK_b,      togglebar,      {0} },
@@ -68,7 +71,7 @@
 	{ MODKEY,                       XK_d,      incnmaster,     {.i = -1 } },
 	{ MODKEY,                       XK_h,      setmfact,       {.f = -0.05} },
 	{ MODKEY,                       XK_l,      setmfact,       {.f = +0.05} },
-	{ MODKEY,                       XK_Return, zoom,           {0} },
+	{ MODKEY,                       XK_Return, swap,           {0} },
 	{ MODKEY,                       XK_Tab,    view,           {0} },
 	{ MODKEY|ShiftMask,             XK_c,      killclient,     {0} },
 	{ MODKEY,                       XK_t,      setlayout,      {.v = &layouts[0]} },
diff -Naur dwm-6.1/drw.h dwm-6.1-patched/drw.h
--- dwm-6.1/drw.h	2015-11-09 06:39:37.000000000 +0800
+++ dwm-6.1-patched/drw.h	2015-12-29 20:54:42.326705599 +0800
@@ -23,6 +23,7 @@
 	Clr *fg;
 	Clr *bg;
 	Clr *border;
+	Clr *mark;
 } ClrScheme;
 
 typedef struct {
diff -Naur 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	2015-12-29 21:04:14.223389631 +0800
@@ -233,6 +233,8 @@
 static int xerrordummy(Display *dpy, XErrorEvent *ee);
 static int xerrorstart(Display *dpy, XErrorEvent *ee);
 static void zoom(const Arg *arg);
+static void setmark(const Arg *arg);
+static void swap(const Arg *arg);
 
 /* variables */
 static const char broken[] = "broken";
@@ -266,6 +268,7 @@
 static Drw *drw;
 static Monitor *mons, *selmon;
 static Window root;
+static Client *mark;
 
 /* configuration, allows nested code to access above variables */
 #include "config.h"
@@ -485,6 +488,7 @@
 		drw_clr_free(scheme[i].border);
 		drw_clr_free(scheme[i].bg);
 		drw_clr_free(scheme[i].fg);
+		drw_clr_free(scheme[i].mark);
 	}
 	drw_free(drw);
 	XSync(dpy, False);
@@ -807,7 +811,10 @@
 		detachstack(c);
 		attachstack(c);
 		grabbuttons(c, 1);
-		XSetWindowBorder(dpy, c->win, scheme[SchemeSel].border->pix);
+		if (c == mark)
+			XSetWindowBorder(dpy, c->win, scheme[SchemeSel].mark->pix);
+		else
+			XSetWindowBorder(dpy, c->win, scheme[SchemeSel].border->pix);
 		setfocus(c);
 	} else {
 		XSetInputFocus(dpy, root, RevertToPointerRoot, CurrentTime);
@@ -1018,6 +1025,8 @@
 {
 	if (!selmon->sel)
 		return;
+	if (mark == selmon->sel)
+		setmark(0);
 	if (!sendevent(selmon->sel, wmatom[WMDelete])) {
 		XGrabServer(dpy);
 		XSetErrorHandler(xerrordummy);
@@ -1065,7 +1074,10 @@
 
 	wc.border_width = c->bw;
 	XConfigureWindow(dpy, w, CWBorderWidth, &wc);
-	XSetWindowBorder(dpy, w, scheme[SchemeNorm].border->pix);
+	if (c == mark)
+		XSetWindowBorder(dpy, w, scheme[SchemeNorm].mark->pix);
+	else
+		XSetWindowBorder(dpy, w, scheme[SchemeNorm].border->pix);
 	configure(c); /* propagates border_width, if size doesn't change */
 	updatewindowtype(c);
 	updatesizehints(c);
@@ -1583,9 +1595,11 @@
 	scheme[SchemeNorm].border = drw_clr_create(drw, normbordercolor);
 	scheme[SchemeNorm].bg = drw_clr_create(drw, normbgcolor);
 	scheme[SchemeNorm].fg = drw_clr_create(drw, normfgcolor);
+	scheme[SchemeNorm].mark = drw_clr_create(drw, normmarkcolor);
 	scheme[SchemeSel].border = drw_clr_create(drw, selbordercolor);
 	scheme[SchemeSel].bg = drw_clr_create(drw, selbgcolor);
 	scheme[SchemeSel].fg = drw_clr_create(drw, selfgcolor);
+	scheme[SchemeSel].mark = drw_clr_create(drw, selmarkcolor);
 	/* init bars */
 	updatebars();
 	updatestatus();
@@ -1745,7 +1759,10 @@
 	if (!c)
 		return;
 	grabbuttons(c, 0);
-	XSetWindowBorder(dpy, c->win, scheme[SchemeNorm].border->pix);
+	if (c == mark)
+		XSetWindowBorder(dpy, c->win, scheme[SchemeNorm].mark->pix);
+	else
+		XSetWindowBorder(dpy, c->win, scheme[SchemeNorm].border->pix);
 	if (setfocus) {
 		XSetInputFocus(dpy, root, RevertToPointerRoot, CurrentTime);
 		XDeleteProperty(dpy, root, netatom[NetActiveWindow]);
@@ -2120,6 +2137,62 @@
 	pop(c);
 }
 
+void
+setmark(const Arg *arg)
+{
+	if (!selmon->sel) {
+		return;
+	}
+	if (selmon->sel == mark) {
+		XSetWindowBorder(dpy, mark->win, scheme[SchemeSel].border->pix);
+		mark = 0;
+	} else {
+		if (mark) {
+			XSetWindowBorder(dpy, mark->win, scheme[SchemeNorm].border->pix);
+			mark = 0;
+		}
+		if (arg && arg->i) {
+			XSetWindowBorder(dpy, selmon->sel->win, scheme[SchemeSel].mark->pix);
+			mark = selmon->sel;
+		}
+	}
+}
+
+void
+swap(const Arg *arg)
+{
+	Client *sel, c;
+
+	if (!mark) {
+		zoom(0);
+		return;
+	}
+	sel = selmon->sel;
+	if (!sel || !selmon->lt[selmon->sellt]->arrange)
+		return;
+	if (mark == sel) {
+		setmark(0);
+		return;
+	}
+	c = *sel;
+	strcpy(sel->name, mark->name);
+	strcpy(mark->name, c.name);
+	sel->win = mark->win;
+	mark->win = c.win;
+
+	XMoveResizeWindow(dpy, sel->win, sel->x + 2 * sw, sel->y, sel->w, sel->h);
+	arrange(sel->mon);
+	XMapWindow(dpy, sel->win);
+	XMoveResizeWindow(dpy, mark->win, mark->x + 2 * sw, mark->y, mark->w, mark->h);
+	arrange(mark->mon);
+	XMapWindow(dpy, mark->win);
+
+	selmon->sel = mark;
+	mark = sel;
+	focus(sel);
+	setmark(0);
+}
+
 int
 main(int argc, char *argv[])
 {