Add isToggleable

Author: Martha Cryan

packages/widgets/src/commandpalette.ts

@@ -652,6 +652,11 @@ namespace CommandPalette {
      */
     readonly isToggled: boolean;
 
+    /**
+     * Whether the command item is toggleable.
+     */
+    readonly isToggleable: boolean;
+
     /**
      * Whether the command item is visible.
      */
@@ -1551,6 +1556,13 @@ namespace Private {
       return this._commands.isToggled(this.command, this.args);
     }
 
+    /**
+     * Whether the command item is toggleable.
+     */
+    get isToggleable(): boolean {
+      return this._commands.isToggleable(this.command, this.args);
+    }
+
     /**
      * Whether the command item is visible.
      */