Remove and Cancel buttons don't work after escaping password prompt

Stesp to reproduce:

• Add Mumble to your additional software.
• Open Additional Software.
• Click the [X] button to remove Mumble.
• Click Remove to confirm.
• At the password prompt press Esc.
• Click Cancel → the Cancel button is broken! (the Remove button as well).

This affected 2 participants during the user testing of the Additional Software beta.

Parent Task: #15567 (closed)

Original created by @sajolida on 15581 (Redmine)