Dragging and dropping selections in the patcher into the document switcher window would be a nifty way to aid in reusing contraptions and a lot more enjoyable than switching documents, copying then pasting. With drag and drop you could select multiple "documents" to drag into your main patcher window at once!
When documents are inserted have them ignore "sound out" if it was wired up previously. In addition to allowing selections to be dragged to the document switcher a "insert selection as new document" and "send to patcher"(?) buttons and keyboard shortcuts(!) would be good.
The way the "insert current document" button works now is hindered by the fact that the "slot" it goes into has to populated with a file already. That is you have to click on the folder icon to load a file first.
Being able to populate the document file(and thus the document switcher) with the contents of folders would also really open up the possibilities of the document switcher. A simple example would be that you could organize different types of devices in different folders and mix and match them. The document files seem to be xml files, so hopefully this wouldn't be too hard. :)
I think these features are in keeping with the spirt of mulch, but would enhance the creative flow.