Fix overflowing titles in the overview

Fix the annoying bug (mostly happening on wayland) in the overview where window titles use more space than what's needed to show the title.

To prevent a regression (window titles are misaligned to the left), don't initially hide the title. This doesn't have to much effect except slightly worsening another bug in the overview (see commit, doesn't seem to be reported yet). This existing bug can only be fixed by completely hiding the overlay from the start, which has been done in !136 (closed).