I like this multiple folder selection, so my suggestion doesn't fit you concept anymore...
But anyway: I usually start TextCrawler via key short-cut when I already have the start folder at hand, either e.g. in Explorer or on the desktop. So it nags me a little bit if I have to browse for it again in TextCrawler's dialogue.
Other window applications support drag and drop, and your folder button even seems to accept a drop event (the mouse cursor changes).
So I'm not sure what a logical place for drop was in your interface, but it would be handy if one could just drag a folder somewhere to enter the start folder location...
drag and drop support for start location
An alternative approach would be adding a right click context menu entry for folders "Search with TextCrawler" like
http://help.lockergnome.com/windows2/ad ... 77246.html
http://windowsxp.mvps.org/context_folders.htm
http://help.lockergnome.com/windows2/ad ... 77246.html
http://windowsxp.mvps.org/context_folders.htm