Ken, this is an interesting bug, as the composite component is quite simple. I haven't looked at it in detail yet but definitely warrants some attention as it is only a problem when singleSubmit is enabled.

Upon further investigation I think this behaviour is limited to ice:selectManyListbox specifically, and how singleSubmit interacts with it. We just happened to see it demonstrated in the dualList composite component.

I tested with a blank ice:selectManyListbox in a simple page with singleSubmit enabled and two POSTs were sent to the server. In the case of dualList this means the add actionListener is called twice.

So when I click the ice:selectManyListbox (regardless of if it's in a composite component or on it's own) an expected POST is done to the server that looks like this:

iceform=iceform&ice.window=m8gjg6egid&ice.view=vdawc31&iceform%3Aicepnltabset%3A0%3Aj_idt60Expanded=&iceform%3Aicepnltabset%3A0%3Aj_idt67Expanded=&iceform%3Aicepnltabset%3A0%3AdualListDemo_leftList=Grapefruit&icefacesCssUpdates=&iceform%3Aj_idcl=&javax.faces.ViewState=-6134776949808937328%3A275458056476100104&javax.faces.source=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&javax.faces.partial.event=click&javax.faces.partial.execute=%40all&javax.faces.partial.render=%40all&ice.window=m8gjg6egid&ice.view=vdawc31&ice.focus=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn=&ice.event.target=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&ice.event.captured=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&ice.event.type=onclick&ice.event.alt=false&ice.event.ctrl=false&ice.event.shift=false&ice.event.meta=false&ice.event.x=857&ice.event.y=471&ice.event.left=true&ice.event.right=false&ice.submit.type=ice.s&ice.submit.serialization=form&javax.faces.partial.ajax=true
(apologies for the formatting)

Nothing unexpected here.

However then I click ANYWHERE else in the page, and a second POST is done. I can click to select a different item, I can click to expand the header, or I can flat out click on the empty background space of the page. When I do that the second POST fires, which looks like this:

vdawc31=vdawc31&icefacesCssUpdates=&javax.faces.ViewState=-6134776949808937328%3A275458056476100104&javax.faces.source=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&javax.faces.partial.execute=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&javax.faces.partial.render=%40all&ice.window=m8gjg6egid&ice.view=vdawc31&ice.focus=&iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn=&ice.event.target=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&ice.event.captured=iceform%3Aicepnltabset%3A0%3AdualListDemo_addBtn&ice.event.type=onunknown&ice.submit.type=ice.se&ice.submit.serialization=element&javax.faces.partial.ajax=true

With dualList this manifest as calling the add actionListener twice. The important info to take from the above POST is:

ice.event.type=onunknown

So it looks like ice:selectManyListbox is firing an unknown event at some point and singleSubmit picks it up and does another POST.

Also note the double POST doesn't happen with h:selectManyListbox, just the ice: version. I thought h: components still took part in singleSubmit, so maybe just the ICEfaces selectManyListbox renderer is the problem.

Further testing was done by explicitly setting partialSubmit="false" on the selectManyListbox. The same double POST happened though. This attempt was done in case the problem components automatically toggled partialSubmit.

Once you hear back from Ted, please test and clean up as needed.

This is only reproducible on IE, is that what you observe?

I was seeing this on Firefox 3.6.13 on Linux as well.

Confirmed in Firefox 3.6 and IE 7. Problem does not occur with Safari, Chrome, or Firefox 4.