I am using the FileDialog() function to let users select multiple
files. After the user chooses all their files and presses the
"Okay" button, my program loops to each chosen file.

Is there an effective way to test when a user chooses an
invalid file type? My users are only allowed to choose
plain text files, hopefully files ending in *.txt. I'm just
looking for ideas how to prevent users from choosing
files that contain non-text data.

Thank you!

Robert