I'm having difficulties with toolbar contributions in a pure e4 application. Some of my toolbar content is defined in the application model. Some additions are contributed through model fragments in the form of TrimContribution elements.

The problem comes with new windows: Whenever I cone a window, it already contains the elements of the original application model and also those that have been contributed through TrimContributions. But then, the TrimContributions are being applied again to the new window resulting in duplicated items.

I have thought about removing everything from the new window's trimbars that was contributed through TrimContributions. But it is not clear how to see whether an item is contributed or not.

Also it is not clear for me whether a pure e4 application should use TrimContributions (and their siblings) at all. Is it better to contribute through direct model extensions than to use TrimContributions? Is it only a feature to allow the compatibility layer to work?

Thanks for clarifications
Peter