Fix filter and search combination error

[timmwille]

In case one adds text into the search bar with preselected "tag" topic and then the text input gets deleted: the text is gone and now all filters are still marked as expected but they have no effect anymore, so one has to clear all filters and apply them again.

Basically this means one can only use either the search or the filters and in combination only when you don't change the search input back.