Interesting, may be a linux bug.
Yes could be a linux bug or could be just my system. Debian is usually rock solid, stable and robust with zero surprises this being said when it does decide to surprise you things are definitely no longer fun
@dbannon: That should be a filter edit (there is a special control). The "Search here" should be .TextHint, i.e. you don't need to clear it...
@Martin_fr please have a look at this, we already have this functionality built in to TListBox:
TListBox built-in search+filter functionality