Add dwm window manager with some initial patches

- Set Mod4 as the mod key and Alacritty as the termcmd.
- Add a patch from suckless.org to hide any vacant tags.
  - https://dwm.suckless.org/patches/hide_vacant_tags

flake.nix

@@ -59,7 +59,7 @@
 
       formatter.${system} = pkgs.nixfmt-rfc-style;
 
-      overlays = import ./nix/overlays { inherit inputs; };
+      overlays = import ./nix/overlays { inherit inputs self; };
 
       nixosModules.default = ./nix/modules/nixos;
 

nix/hosts/t490/services/default.nix

@@ -1,11 +1,10 @@
-{ ... }:
-
 {
   imports = [
+    ./dwm.nix
     ./interception-tools.nix
     ./sound.nix
-    ./xserver.nix
     ./udev.nix
+    ./xserver.nix
   ];
 
   services = {

nix/hosts/t490/services/dwm.nix

@@ -0,0 +1,27 @@
+{ pkgs, ... }:
+
+{
+  services = {
+    dwm-status = {
+      enable = true;
+
+      order = [
+        "audio"
+        "backlight"
+        "battery"
+        "cpu_load"
+        "network"
+        "time"
+      ];
+    };
+
+    xserver.windowManager.dwm.enable = true;
+  };
+
+  environment.systemPackages = with pkgs; [
+    dmenu
+    dmenu-bluetooth
+    networkmanager_dmenu
+    st
+  ];
+}

nix/overlays/default.nix

@@ -1,4 +1,4 @@
-{ inputs, ... }:
+{ inputs, self, ... }:
 
 {
   additions =
@@ -9,7 +9,15 @@
       pkgs = final;
     };
 
-  modifications = final: prev: { };
+  modifications = final: prev: {
+    dwm = prev.dwm.override {
+      patches = [
+        "${self}/patches/dwm/change-mod-key.patch"
+        "${self}/patches/dwm/change-termcmd.patch"
+        "${self}/patches/dwm/dwm-hide_vacant_tags-6.4.diff"
+      ];
+    };
+  };
 
   stable-packages = final: _prev: {
     nixpkgs-2405 = import inputs.nixpkgs-2405 {

patches/dwm/change-mod-key.patch

@@ -0,0 +1,13 @@
+diff --git a/config.def.h b/config.def.h
+index 9efa774..4412cb1 100644
+--- a/config.def.h
++++ b/config.def.h
+@@ -45,7 +45,7 @@ static const Layout layouts[] = {
+ };
+ 
+ /* key definitions */
+-#define MODKEY Mod1Mask
++#define MODKEY Mod4Mask
+ #define TAGKEYS(KEY,TAG) \
+ 	{ MODKEY,                       KEY,      view,           {.ui = 1 << TAG} }, \
+ 	{ MODKEY|ControlMask,           KEY,      toggleview,     {.ui = 1 << TAG} }, \

patches/dwm/change-termcmd.patch

@@ -0,0 +1,13 @@
+diff --git a/config.def.h b/config.def.h
+index 9efa774..648336e 100644
+--- a/config.def.h
++++ b/config.def.h
+@@ -58,7 +58,7 @@ static const Layout layouts[] = {
+ /* commands */
+ static char dmenumon[2] = "0"; /* component of dmenucmd, manipulated in spawn() */
+ static const char *dmenucmd[] = { "dmenu_run", "-m", dmenumon, "-fn", dmenufont, "-nb", col_gray1, "-nf", col_gray3, "-sb", col_cyan, "-sf", col_gray4, NULL };
+-static const char *termcmd[]  = { "st", NULL };
++static const char *termcmd[]  = { "alacritty", NULL };
+ 
+ static const Key keys[] = {
+ 	/* modifier                     key        function        argument */

patches/dwm/dwm-hide_vacant_tags-6.4.diff

@@ -0,0 +1,48 @@
+:100644 100644 f1d86b2 0000000 M	dwm.c
+
+diff --git a/dwm.c b/dwm.c
+index f1d86b2..d41cc14 100644
+--- a/dwm.c
++++ b/dwm.c
+@@ -433,9 +433,15 @@ buttonpress(XEvent *e)
+ 	}
+ 	if (ev->window == selmon->barwin) {
+ 		i = x = 0;
+-		do
++		unsigned int occ = 0;
++		for(c = m->clients; c; c=c->next)
++			occ |= c->tags == TAGMASK ? 0 : c->tags;
++		do {
++			/* Do not reserve space for vacant tags */
++			if (!(occ & 1 << i || m->tagset[m->seltags] & 1 << i))
++				continue;
+ 			x += TEXTW(tags[i]);
+-		while (ev->x >= x && ++i < LENGTH(tags));
++		} while (ev->x >= x && ++i < LENGTH(tags));
+ 		if (i < LENGTH(tags)) {
+ 			click = ClkTagBar;
+ 			arg.ui = 1 << i;
+@@ -715,19 +721,18 @@ drawbar(Monitor *m)
+ 	}
+ 
+ 	for (c = m->clients; c; c = c->next) {
+-		occ |= c->tags;
++		occ |= c->tags == TAGMASK ? 0 : c->tags;
+ 		if (c->isurgent)
+ 			urg |= c->tags;
+ 	}
+ 	x = 0;
+ 	for (i = 0; i < LENGTH(tags); i++) {
++		/* Do not draw vacant tags */
++		if(!(occ & 1 << i || m->tagset[m->seltags] & 1 << i))
++			continue;
+ 		w = TEXTW(tags[i]);
+ 		drw_setscheme(drw, scheme[m->tagset[m->seltags] & 1 << i ? SchemeSel : SchemeNorm]);
+ 		drw_text(drw, x, 0, w, bh, lrpad / 2, tags[i], urg & 1 << i);
+-		if (occ & 1 << i)
+-			drw_rect(drw, x + boxs, boxs, boxw, boxw,
+-				m == selmon && selmon->sel && selmon->sel->tags & 1 << i,
+-				urg & 1 << i);
+ 		x += w;
+ 	}
+ 	w = TEXTW(m->ltsymbol);

patches/dwm/dwm-switchtotag-6.2.diff

@@ -0,0 +1,58 @@
+diff -up dwm-6.2-original/config.def.h dwm-6.2-modified/config.def.h
+--- dwm-6.2-original/config.def.h	2019-02-02 14:55:28.000000000 +0200
++++ dwm-6.2-modified/config.def.h	2019-11-18 19:36:22.515566509 +0200
+@@ -26,9 +26,9 @@ static const Rule rules[] = {
+ 	 *	WM_CLASS(STRING) = instance, class
+ 	 *	WM_NAME(STRING) = title
+ 	 */
+-	/* class      instance    title       tags mask     isfloating   monitor */
+-	{ "Gimp",     NULL,       NULL,       0,            1,           -1 },
+-	{ "Firefox",  NULL,       NULL,       1 << 8,       0,           -1 },
++	/* class      instance    title       tags mask     switchtotag    isfloating   monitor */
++	{ "Gimp",     NULL,       NULL,       0,            0,             1,           -1 },
++	{ "Firefox",  NULL,       NULL,       1 << 8,       0,             0,           -1 },
+ };
+ 
+ /* layout(s) */
+diff -up dwm-6.2-original/dwm.c dwm-6.2-modified/dwm.c
+--- dwm-6.2-original/dwm.c	2019-02-02 14:55:28.000000000 +0200
++++ dwm-6.2-modified/dwm.c	2019-11-18 19:37:18.792187705 +0200
+@@ -92,6 +92,7 @@ struct Client {
+ 	int basew, baseh, incw, inch, maxw, maxh, minw, minh;
+ 	int bw, oldbw;
+ 	unsigned int tags;
++	unsigned int switchtotag;
+ 	int isfixed, isfloating, isurgent, neverfocus, oldstate, isfullscreen;
+ 	Client *next;
+ 	Client *snext;
+@@ -137,6 +138,7 @@ typedef struct {
+ 	const char *instance;
+ 	const char *title;
+ 	unsigned int tags;
++	unsigned int switchtotag;
+ 	int isfloating;
+ 	int monitor;
+ } Rule;
+@@ -302,6 +304,11 @@ applyrules(Client *c)
+ 			for (m = mons; m && m->num != r->monitor; m = m->next);
+ 			if (m)
+ 				c->mon = m;
++			if (r->switchtotag) {
++				Arg a = { .ui = r->tags };
++				c->switchtotag = selmon->tagset[selmon->seltags];
++				view(&a);
++			}
+ 		}
+ 	}
+ 	if (ch.res_class)
+@@ -1782,6 +1789,10 @@ unmanage(Client *c, int destroyed)
+ 	focus(NULL);
+ 	updateclientlist();
+ 	arrange(m);
++	if (c->switchtotag) {
++		Arg a = { .ui = c->switchtotag };
++		view(&a);
++	}
+ }
+ 
+ void