Editor Menubar Example: Enter not closing menus when performing a command and aria-checked not correctly set on some items

[mcking65]

This issue is for two bugs in the editor menubar example:

1. When Enter is pressed to activate a menuitem that performs an action, e.g., change font, it should both perform the action and close the menu. In this particular example, the focus should logicaly go to the text area after the action is performed.

2. When menuitem radios and menuitemcheckbox items are activated, sometimes the aria-checked state is not set to true. And, if a menuitemradio, the previously checked item does not get aria-checked set to false. This was working correctly prior to commit 0de93bd.

[mcking65]

With thanks to @sh0ji, this is resolved with commit ba84ee6.