tags should be persistent now during X server run

dwm.h

@@ -81,7 +81,7 @@ extern int wax, way, wah, waw;			/* windowarea geometry */
 extern unsigned int bh, blw, bpos;		/* bar height, bar layout label width, bar position */
 extern unsigned int ntags, numlockmask;		/* number of tags, numlock mask */
 extern void (*handler[LASTEvent])(XEvent *);	/* event handler */
-extern Atom wmatom[WMLast], netatom[NetLast];
+extern Atom dwmtags, wmatom[WMLast], netatom[NetLast];
 extern Bool selscreen, *seltag;			/* seltag is array of Bool */
 extern Client *clients, *sel, *stack;		/* global client list and stack */
 extern Cursor cursor[CurLast];

layout.c

@@ -2,6 +2,8 @@
 #include "dwm.h"
 #include <stdlib.h>
 
+/* static */
+
 typedef struct {
 	const char *symbol;
 	void (*arrange)(void);
@@ -10,10 +12,8 @@ typedef struct {
 unsigned int blw = 0;
 static Layout *lt = NULL;
 
-/* static */
-
 static void
-floating(void) {
+floating(void) { /* default floating layout */
 	Client *c;
 
 	for(c = clients; c; c = c->next)

main.c

@@ -19,7 +19,7 @@ int screen, sx, sy, sw, sh, wax, way, waw, wah;
 unsigned int bh, ntags;
 unsigned int bpos = BARPOS;
 unsigned int numlockmask = 0;
-Atom wmatom[WMLast], netatom[NetLast];
+Atom dwmtags, wmatom[WMLast], netatom[NetLast];
 Bool *seltag;
 Bool selscreen = True;
 Client *clients = NULL;
@@ -139,6 +139,7 @@ setup(void) {
 	XSetWindowAttributes wa;
 
 	/* init atoms */
+	dwmtags = XInternAtom(dpy, "__DWM_TAGS", False);
 	wmatom[WMProtocols] = XInternAtom(dpy, "WM_PROTOCOLS", False);
 	wmatom[WMDelete] = XInternAtom(dpy, "WM_DELETE_WINDOW", False);
 	wmatom[WMState] = XInternAtom(dpy, "WM_STATE", False);

tag.c

@@ -3,6 +3,8 @@
 #include <regex.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <X11/Xatom.h>
 #include <X11/Xutil.h>
 
 /* static */
@@ -23,6 +25,7 @@ RULES
 
 static Regs *regs = NULL;
 static unsigned int nrules = 0;
+static char prop[512];
 
 /* extern */
 
@@ -65,16 +68,32 @@ isvisible(Client *c) {
 
 void
 settags(Client *c, Client *trans) {
-	char prop[512];
 	unsigned int i, j;
 	regmatch_t tmp;
 	Bool matched = trans != NULL;
 	XClassHint ch = { 0 };
+	XTextProperty name;
 
-	if(matched)
+	if(matched) {
 		for(i = 0; i < ntags; i++)
 			c->tags[i] = trans->tags[i];
+		return;
+	}
 	else {
+		/* check if window has set a property */
+		name.nitems = 0;
+		XGetTextProperty(dpy, c->win, &name, dwmtags);
+		if(name.nitems && name.encoding == XA_STRING) {
+			strncpy(prop, (char *)name.value, sizeof prop - 1);
+			prop[sizeof prop - 1] = '\0';
+			XFree(name.value);
+			for(i = 0; i < ntags && i < sizeof prop - 1 && prop[i] != '\0'; i++)
+				if((c->tags[i] = prop[i] == '+'))
+					matched = True;
+		}
+		if(matched)
+			return;
+		/* rule matching */
 		XGetClassHint(dpy, c->win, &ch);
 		snprintf(prop, sizeof prop, "%s:%s:%s",
 				ch.res_class ? ch.res_class : "",
@@ -110,6 +129,12 @@ tag(const char *arg) {
 	i = arg ? atoi(arg) : 0;
 	if(i >= 0 && i < ntags)
 		sel->tags[i] = True;
+	if(sel) {
+		for(i = 0; i < ntags && i < sizeof prop - 1; i++)
+			prop[i] = sel->tags[i] ? '+' : '-';
+		prop[i] = '\0';
+		XChangeProperty(dpy, sel->win, dwmtags, XA_STRING, 8, PropModeReplace, (unsigned char *)prop, i);
+	}
 	arrange();
 }