Closing BT Client Scan?

I would like to close the BT Client scan and display a ShowMessageDialog that no BT device has been found...
I can check if the BT device list is empty, and there is an example here that shows how to populate the BT Addresses list with lines of a text message, but you then have to backspace the screen to get out of the Scan list and return to the App screen.
It seems that once you launch 'call' the only mechanism to exit is a 'scan.Afterpicking' selection, or a 'back screen'.
Is there a method to 'call', test for an empty list of BT_addresses, display a ShowMessageDialog box, and do a 'scan.close' when the message dialog button is clicked?

Use a listview instead of a listpicker, then you remain on the app screen ?

Interesting idea...... I will try that. Thanks