File > Run crash after selecting non-runnable file

[inexorabletash]

Repro

1. Configure Shortcuts (selector) to run on startup
2. Invoke DESKTOP.SYSTEM
3. File > Run
4. Pick a non-runnable file e.g. a folder
5. Click OK
6. Alert appears "Unable to run the program"
7. Click OK
8. Alert dismisses
9. Click OK again

Result: application crashes

Initial Analysis

When OK is clicked in the file dialog control returns to the app. The app tries to launch the file, but fails and shows the dialog. Control is returned to the file dialog loop via jsr file_dialog_loop but something goes awry. Need to debug further.

[inexorabletash]

The Alert's use of $800 ... $1C00 as Save Area (for quickly restoring the background) is trashing the File Dialog's state starting at $1600 (current path specifically, but also filenames etc)