4.0.0w Snapshot fails to select additional main for existing project

When attempting to add additional main subprogram to an existing project, gps is unable to select the selected file, no check mark on the file. Here is the scenario used.  From an existing project, select Project -> Edit Project Properties. Then, select Main files tab then select +Add button. Select files dialog box comes up displaying a list of files. Select one of these files. The check mark fails to show up.

AV