[MenuButton, SplitMenuButton] Selection is not preserved.

MenuButton and SplitMenuButton doesn't save selection.

I read in instruction for tests:
1. Click the arrow button and hover the mouse onto the popup till the 4th menu item and click it.
2. Click some where on the stage , then click the arrow button again this time you should see 4th item must be selected default.

Also, some part of specifiaction is not applied:
2. pop-up menu button. It allows users to change the function of the main button by selecting items from the pop-up menu. The most recently selected item becomes the main button item.