Do we want this to fire as well when the submenu is opened by simply hovering over it?

Do we want to add a custom onClick attribute as well (just like ace:menuItem)?

Committed improvement to 3.3 EE maintenance branch at revision 43597 and to 4.0 trunk at revision 43598. Added actionListener, ajax event, and onclick attribute to ace:submenu.

Testing Notes: These features are meant to be activated only when clicking on the submenu labels (i.e. not when hovering). Note that the ajax event name is 'activate' in 3.3 and 'action' in 4.0.

New ace:submenu ajax tests have been added to ace:menu QA test application, test page: /menuAjax.jsf.

Menu QA Test app for IF4 trunk:
http://dev.icesoft.com/svn/repo/qa/trunk/Regression-Icefaces4/Sparkle/Nightly/menu
Menu QA test app for EE-3.3-maintenance:
http://dev.icesoft.com/svn/repo/qa/trunk/Regression-Icefaces2/Sparkle/Nightly/menu

Re-opening because of these failures:

1) These Ajax tests fail on both IF4 trunk & EE-3.3-maintenance:
Submenu ActionListener attribute only
Submenu Action attribute only

2) The following submenu ajax tests cause server errors (NullPointerException) on IF4 trunk (not an issue on EE-3.3-mainetnance where they pass):
Submenu "action" Event Test (Default render/execute)
Submenu "action" Event Test (execute=@all render=@all)
Submenu Default Event Test (execute=@all render=@all)
Submenu "action" Event Test w/ ActionListener attribute (Default execute/render)
Submenu "action" Event Test w/ Action attribute (Default execute/render)
Submenu "action" Event Test w/ Ajax Disabled (execute=@all render=@all)

java.lang.NullPointerException
org.icefaces.ace.component.submenu.Submenu.getScript(Submenu.java:90)
org.icefaces.ace.component.menu.MenuRenderer.encodePlainSubmenu(MenuRenderer.java:296)
org.icefaces.ace.component.menu.MenuRenderer.encodePlainMenuContent(MenuRenderer.java:257)
org.icefaces.ace.component.menu.MenuRenderer.encodeMarkup(MenuRenderer.java:154)
org.icefaces.ace.component.menu.MenuRenderer.encodeEnd(MenuRenderer.java:57)
javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:919)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
org.icefaces.impl.renderkit.RendererWrapper.encodeChildren(RendererWrapper.java:49)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:114)
javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)
com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)

New ajax submenu tests have been added to ace:menuBar and ace:contextMenu QA test apps.
Testing results:
EE-3.3.0-maintenance branch r43606: all tests pass.
IF4 trunk r 43616: ajax tests fail because of the same NullPointerException.

Committed fixes for exceptions and for action/actionListener at revisions 43634 and 43535.

Verified with IF4 trunk / EE-3.3 r43636 in IE10, CHrome39, FF34: all ajax submenu tests for ace:menu/menuBar/contextMenu pass.