#20 Open Dialog can be opened many times

[Johnathan James]

1. Open the Editor
2. Click on File > Open
3. Move the Open dialog out of the way, and click in
the main window.
4. Click on File > Open and you get a second Open
dialog. Repeat as many times as desired.

You should only be able to open one Open dialog, and
you should not be able to click in the main window
until the Open dialog is closed.