This C# program is a very simple tool for randomly displaying quiz lines in the top text box from a user-created file. The user can then conjure his response and click again to proceed to select another quiz line. If the user can't remember the correct response, he/she can click the lower text box to get the correct answer. The user-created file consists of lines of quiz text, each followed by a line of hint/help text. So the user-created file should have an even number of lines. The line...