refactor!: Add setSelectedItem() to IToolbox.

core/interfaces/i_toolbox.ts

@@ -94,7 +94,7 @@ export interface IToolbox extends IRegistrable {
   setVisible(isVisible: boolean): void;
 
   /**
-   * Selects the toolbox item by it's position in the list of toolbox items.
+   * Selects the toolbox item by its position in the list of toolbox items.
    *
    * @param position The position of the item to select.
    */
@@ -107,6 +107,14 @@ export interface IToolbox extends IRegistrable {
    */
   getSelectedItem(): IToolboxItem | null;
 
+  /**
+   * Sets the selected item.
+   *
+   * @param item The toolbox item to select, or null to remove the current
+   *     selection.
+   */
+  setSelectedItem(item: IToolboxItem | null): void;
+
   /** Disposes of this toolbox. */
   dispose(): void;
 }