choose-new-file-dialog bug

["Mark A. Tapia" <markt@dgp.toronto.edu>]

When attempting to replace an existing file, the function 
choose-new-file-dialog does not repaint the portion of the dialog box
covered by the "Replace existing file" prompt.

As a result the user cannot see the lower portion of the scrolling region
(including the arrows and scroll bars) and the editable text field.

This problem does not occur for the File Menu item "Save As...".     

mark