I found this to be a requirement in my application: if the user clicks the label part of a LinkButton, the button should fire immediately without showing the popup, thus invoking the action with the currently selected entry. If the user clicks the triangle part, the popup should be shown.
I patched LinkButton to add a new boolean property called "showPopupOnTriggerClickOnly" to TerraListButtonSkin (I couldn't think of a better name, sorry). If set to true, the ListButton popup will only show up if the user clicks the triangle, but not if the user clicks the rest of the button. However, ButtonPressListeners fire as usual, if the user clicks any part of the button. If the property is false, the behavior is as it was before. The default value of the property is false.
I tested the patch in my application and ComponentExplorer and it works good.
It would be nice if you integrate the patch. Otherwise I'd still have the option to write a custom skin, but I think this patch could be interesting to other developers as well.