If you had that automatic toolbar as a part of a row, it would still pop up on that half, and otherwise leave a gap, which might be equally irritating. Maybe the best solution would be, to permanently integrate the commands you need, somewhere in an existing toolbar. And the LINE command for toolbar positions doesn't work with automatic file type recognition, which always triggers a full row toolbar.
http://www.gpsoft.com.au/help/opus11/index.html#!Documents/Toolbar.htm