Closes #3098.
Sadly there is not a nice way of fixing this.
There is the issue that in some cases that the ui thread blocked.
Makes showing up the header immediately possible
+ update all its references
# Conflicts: # osu.Game/Overlays/Chat/ChatTabControl.cs # osu.Game/Overlays/ChatOverlay.cs
Add missing accessibility modifier in ClickableText test case and fix disposal