dwm: add extraSessionCommands option

Author: pinn3

nixos/modules/services/x11/window-managers/dwm.nix

@@ -15,6 +15,13 @@ in
   options = {
     services.xserver.windowManager.dwm = {
       enable = mkEnableOption "dwm";
+      extraSessionCommands = mkOption {
+        default     = "";
+        type        = types.lines;
+        description = ''
+          Shell commands executed just before dwm is started.
+        '';
+      };
       package = mkPackageOption pkgs "dwm" {
         example = ''
           pkgs.dwm.overrideAttrs (oldAttrs: rec {
@@ -39,6 +46,8 @@ in
       { name = "dwm";
         start =
           ''
+            ${cfg.extraSessionCommands}
+
             export _JAVA_AWT_WM_NONREPARENTING=1
             dwm &
             waitPID=$!