Here are some more details, that could help people answering my question:

I've understood that the line <contentView name="document_content"> (see the URL above) overrides the default document view and so it is called everywhere. If i change the name to something else the custom view is no longer called. Now, how should I call that content view from the xml contribution of an Action Seam, so this is called only when I want to (when I press a button or click a tab)?

I have the same problem and i can't find documentation about this question. There is someone in nuxeo that can help us to solve this problem? Thank you!

hi, sorry "activating" or "applying" a content view is not meaningful to me. i don't get what you'd like to do.

Let's put it in another way:

I want a tab or a button in my interface that, if clicked, shows me all the documents in the DM that match a certain criteria (for example: all the documents older than 1 year). I noticed that I can filter content defining a NXQL query inside a content view and I made a test following the example on the link above. It works but the content view is called as the default one. I don't know if it's possible (and if it's not please suggest me another workflow) to show that content view, with the custom query only when the user clicks a button, and the default "folderish" content view in all the other cases. Can you help me?

if i understand you want to switch the rendering of the content view depending on if user clicks on a button. maybe you can just show the alternative content view in a new tab?

Sorry for the late reply. If i define a content view it queries the current workspace. I would like to query the entire DM for all results that match a certain criteria. For now I solved this with the Smart Search plugin, creating a "smart folder", but I would be interested in knowing how it should be done in general.