Infinite loop after aborting on Scan Topic Dialog

[allgood]

If hit the back button on "Scan Topic" dialog (implemented on 554b25e by @thrillfall ) , the dialog disappears and the activity is unusable until the application is kiled.

Steps to reproduce

Select the "custom scan topic" option on settings page, scan an image and when presented the dialog to set the topic just hit the android Back action button

Expected behaviour

Application returns to main activity ready to scan another image.

Actual behaviour

Application returns to main activity with a "waiting" icon that never disappears and are unable to scan new images.

[allgood]

Fixed on commit a3f2fb9