Use the Changed Sources dialog box to specify those files which are
 to be regarded as changed.

 The right-hand list box contains a list of the possible source files
 to choose from to insert into the Changed Sources List.
 Initially, the selection list box lists all the source files in the
 current default directory.  But, there is the option of picking a
 different directory to list the files from.  These options are
 available by clicking the corresponding radio button.

 Any file in the right-hand list box that is double-clicked is inserted
 into the left-hand list box.  The left arrow button can also be used
 for moving a file from the right-hand box to the left-hand box.  Clicking
 the All button will move all the files listed in the right-hand box to
 the left-hand box.

 Source files can be removed from or up in the left-hand list by means of
 arrow buttons (which are displayed when a file is highlighted).