How to reproduce it :

• open the search panel
• put the focus on the title field then quit this input text > to make it you will probably click above the field where there is nothing.
  If you click on the red zone (see the srceenshot), the search criteria close like if a search would have been launch.

The cliquable zone should change the cursor on the mouseover and the whole width of the title should be more visible to understand this behavior.