added swap focus patch

dwm.c

@@ -207,6 +207,7 @@ static void seturgent(Client *c, int urg);
 static void showhide(Client *c);
 static void sigchld(int unused);
 static void spawn(const Arg *arg);
+static void swapfocus();
 static void tag(const Arg *arg);
 static void tagmon(const Arg *arg);
 static void tile(Monitor *);
@@ -241,6 +242,7 @@ static void bstack(Monitor *m);
 static void bstackhoriz(Monitor *m);
 
 /* variables */
+static Client *prevclient = NULL;
 static const char broken[] = "broken";
 static char stext[256];
 static int screen;
@@ -1672,6 +1674,17 @@ spawn(const Arg *arg)
 	}
 }
 
+void
+swapfocus()
+{
+	Client *c;
+	for(c = selmon->clients; c && c != prevclient; c = c->next) ;
+	if(c == prevclient) {
+		focus(prevclient);
+		restack(prevclient->mon);
+	}
+}
+
 void
 tag(const Arg *arg)
 {
@@ -1789,6 +1802,7 @@ unfocus(Client *c, int setfocus)
 {
 	if (!c)
 		return;
+	prevclient = c;
 	grabbuttons(c, 0);
 	XSetWindowBorder(dpy, c->win, scheme[SchemeNorm][ColBorder].pixel);
 	if (setfocus) {
@@ -2177,12 +2191,13 @@ void
 zoom(const Arg *arg)
 {
 	Client *c = selmon->sel;
+	prevclient = nexttiled(selmon->clients);
 
 	if (!selmon->lt[selmon->sellt]->arrange
 	|| (selmon->sel && selmon->sel->isfloating))
 		return;
 	if (c == nexttiled(selmon->clients))
-		if (!c || !(c = nexttiled(c->next)))
+		if (!c || !(c = prevclient = nexttiled(c->next)))
 			return;
 	pop(c);
 }

patches/dwm-swapfocus-20160731-56a31dc.diff

@@ -0,0 +1,67 @@
+Author: Jan Christoph Ebersbach <jceb@e-jc.de>
+URL: http://dwm.suckless.org/patches/swapfocus
+This patch makes it possible to switch focus with one single shortcut (alt-s)
+instead of having to think if you should use alt-j or alt-k for reaching the
+last used window.
+
+Index: dwm/dwm.c
+===================================================================
+--- dwm/dwm.c.orig
++++ dwm/dwm.c
+@@ -207,6 +207,7 @@ static void setup(void);
+ static void showhide(Client *c);
+ static void sigchld(int unused);
+ static void spawn(const Arg *arg);
++static void swapfocus();
+ static void tag(const Arg *arg);
+ static void tagmon(const Arg *arg);
+ static void tile(Monitor *);
+@@ -236,6 +237,7 @@ static int xerrorstart(Display *dpy, XEr
+ static void zoom(const Arg *arg);
+ 
+ /* variables */
++static Client *prevclient = NULL;
+ static const char broken[] = "broken";
+ static char stext[256];
+ static int screen;
+@@ -1645,6 +1647,17 @@ spawn(const Arg *arg)
+ }
+ 
+ void
++swapfocus()
++{
++	Client *c;
++	for(c = selmon->clients; c && c != prevclient; c = c->next) ;
++	if(c == prevclient) {
++		focus(prevclient);
++		restack(prevclient->mon);
++	}
++}
++
++void
+ tag(const Arg *arg)
+ {
+ 	if (selmon->sel && arg->ui & TAGMASK) {
+@@ -1743,6 +1756,7 @@ unfocus(Client *c, int setfocus)
+ {
+ 	if (!c)
+ 		return;
++	prevclient = c;
+ 	grabbuttons(c, 0);
+ 	XSetWindowBorder(dpy, c->win, scheme[SchemeNorm][ColBorder].pixel);
+ 	if (setfocus) {
+@@ -2109,12 +2123,13 @@ void
+ zoom(const Arg *arg)
+ {
+ 	Client *c = selmon->sel;
++	prevclient = nexttiled(selmon->clients);
+ 
+ 	if (!selmon->lt[selmon->sellt]->arrange
+ 	|| (selmon->sel && selmon->sel->isfloating))
+ 		return;
+ 	if (c == nexttiled(selmon->clients))
+-		if (!c || !(c = nexttiled(c->next)))
++		if (!c || !(c = prevclient = nexttiled(c->next)))
+ 			return;
+ 	pop(c);
+ }