Basic scratch toggle

Stack ordering isn't preserved properly. Use <Super>e to toggle for now.

extension.js

@@ -1,6 +1,7 @@
 const Extension = imports.misc.extensionUtils.getCurrentExtension();
 const convenience = Extension.imports.convenience;
 const Tiling = Extension.imports.tiling;
+const Scratch = Extension.imports.scratch;
 const utils = Extension.utils;
 const Gio = imports.gi.Gio;
 const Meta = imports.gi.Meta;
@@ -84,6 +85,7 @@ function enable() {
     // Must use `Meta.keybindings_set_custom_handler` to re-assign handler?
     set_action_handler("move-left", dynamic_function_ref("move_left"));
     set_action_handler("move-right", dynamic_function_ref("move_right"));
+    set_action_handler("toggle-scratch-layer", dynamic_function_ref("toggleScratch"));
 }
 
 function disable() {

scratch.js

@@ -0,0 +1,25 @@
+const Meta = imports.gi.Meta;
+
+toggleScratch = function() {
+    let workspace = global.screen.get_active_workspace()
+    let windows = global.display.get_tab_list(Meta.TabList.NORMAL, workspace)
+        .filter(function(meta_window) {
+            return meta_window.is_on_all_workspaces();
+        });
+
+    let isSomeShown = windows.reduce(function(shown, meta_window) {
+        return shown || !meta_window.minimized;
+    }, false)
+
+    if (isSomeShown) {
+        windows.map(function(meta_window) {
+            meta_window.minimize();
+        })
+    } else {
+        windows.map(function(meta_window) {
+            meta_window.unminimize();
+            meta_window.make_above();
+        })
+        windows[0].activate(global.get_current_time())
+    }
+}