GHOP - allow multiple tag selection

It would be nice if it was possible to concate several tags. So for example you select Tag x. Then you get a long list of nodes. maybe within this node you now want to make a finer selection and add another tag from the cloud. So beside every tag there need to be a little plus that makes it possible to add a tag to the current selection.

I hope this was clear. For demonstration check out http://nickiplorer.schaerwebdesign.ch -> search for something then you get a selection of tags that allow you to refine the search.