sway: enable xwayland (but not for sxmo)

hosts/modules/gui/sway/default.nix

@@ -39,6 +39,9 @@ in
           bindsym --locked XF86AudioLowerVolume exec $volume_down
         '';
       };
+      background = mkOption {
+        type = types.path;
+      };
       font = mkOption {
         type = types.string;
         default = "pango:monospace 11";
@@ -46,9 +49,6 @@ in
           default font (for e.g. window titles)
         '';
       };
-      background = mkOption {
-        type = types.path;
-      };
       mod = mkOption {
         type = types.string;
         default = "Mod4";
@@ -68,6 +68,14 @@ in
           - etc
         '';
       };
+      xwayland = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          whether or not to enable xwayland (allows running X11 apps on sway).
+          some electron apps (e.g. element-desktop) require xwayland.
+        '';
+      };
 
       # TODO: split these into their own option scope
       brightness_down_cmd = mkOption {

hosts/modules/gui/sway/sway-config.nix

@@ -20,8 +20,6 @@ let
   '';
   # TODO: splatmoji release > 1.2.0 should allow `-s none` to disable skin tones
   emoji_cmd = "${pkgs.splatmoji}/bin/splatmoji -s medium-light type";
-
-  xwayland = "disable";
 in pkgs.substituteAll {
   src = ./sway-config;
   inherit
@@ -33,7 +31,6 @@ in pkgs.substituteAll {
     terminal_cmd
     vol_down_cmd
     vol_up_cmd
-    xwayland
   ;
   inherit (config)
     background
@@ -46,6 +43,7 @@ in pkgs.substituteAll {
     mod
     workspace_layout
   ;
+  xwayland = if config.xwayland then "enable" else "disable";
   playerctl = "${pkgs.playerctl}/bin/playerctl";
   waybar = "${pkgs.waybar}/bin/waybar";
 }

hosts/modules/gui/sxmo/default.nix

@@ -211,9 +211,11 @@ in
             # - `bindsym $mod+Shift+p exec sxmo_appmenu.sh sys`
             # - `input * xkb_options compose:ralt`
             # these could be added, but i don't see much benefit.
-            mod = "Mod1";  # prefer Alt
             font = "Sxmo 10";
+            mod = "Mod1";  # prefer Alt
+            xwayland = false;  # disable to reduce RAM usage.
             workspace_layout = "tabbed";
+
             brightness_down_cmd = "sxmo_brightness.sh down";
             brightness_up_cmd = "sxmo_brightness.sh up";
             screenshot_cmd = "sxmo_screenshot.sh";