Improve filter function of tickets

Problem/Motivation

Currently, we use a drop-down to indicate whether we should display resolved tickets or not. We also have a text field to type the title of a ticket. You must click the apply button to start the search. We want to improve the UX here.

Proposed resolution

Provide a checkbox instead of a drop-down list, which only contains two values anyway.

Furthermore, the result list should adapt without the need of clicking the apply button.
We might check the better exposed filter module.