and the renderer creates a toolItem with the dropdown-arrow in the toolbar but clicking on the arrow does not have any effect.
I know there are bugs existing in the MenuRenderers regarding adding/removing Items at runtime, so I closed my application and started it again to directly create the toolitem from the serialized workbench-model but the arrow of the toolitem was still not clickable.
Iam using the Platform Runtime Repo (category: Platform Runtime Binary) from 4.2 release build (http://download.eclipse.org/eclipse/downloads/drops4/R-4.2-201206081400/) in my target platform and the Eclipse SDK for Windows from the same version for developing the application. Iam not sure what you mean by "tools".
Java Development Tools build ID is I20120608-1400
org.eclipse.e4.tools version is 0.12.0.v20120529-2033