Highlight region and keyboard insertion point get mismatched in fileopen dialog box

[Albert Wong <awong@cs.washington.edu>]

I noticed that in Source Navigator 4.5.1, if you have a text region
highlighted in a file open dialog box's "File name" input field, move
focus away from the file name input box (lick click on the graphical
browser part) and then move back to highlight a subsegment of the "File
name" text, the keyboard insert point moves to the end of the text
ignoring the highlight region.  This is somewhat annoying because when you
type, you insert at the end of the text, but the highlighted region still
disappears.  
	It looks like the highlight region and the text region are 
ignoring the initial mouse click (as the highlight always starts from the
left and the text insert's always on the furthest right), and the cursor
ignores subsequent dragging. Perhaps it should follow the mouse location
more closely so that if you can highlight an arbitrary section rather than
a section from the beginning of the text.

To reproduce this:
 - Get to a file open dialog box somehow (like File|Open Project)
 - Type in something in the filename field
 - click on  a folder
 - try to select a sub region (before the last char) of what you typed
 - type something else, which you'd expect to replace the highlighted text


-Albert