(im using facets)

if i click on a file outside of foobar (in a directory) then that file gets loaded up in foobar and clears everything that was loaded in the 'library' display facets (genre,artist,songs) and just the clicked file is displayed...

the library is still available to foobar (if i go to menu>library>album list everything is there)
but how do i re-add this in the displayed facets, instead of that on file which "took over" ?

I don't really know what you mean by clicking a file outside of foobar and 'library display', but I give you all the options that cover wat I think you mean to ask...

(Double)click on All (of the facet that you want to reset to "virgin" state) that is in the top of every facet and says for example: All (25 genres)
(doubleclick updates facets playlist, click updates facets window)

For incoming files (files that you selected in a directory) you can specify a playlist it has to go in. (so it won't take over the active facets playlist).

Go to preferences > general > Always send to playlist.
Make sure that's active, and give it any name you want, but not Facet Selection.

Also go to preferences > media library > Library Viewer selection and deselect that if you don't want album list to take over your facets playlist if you click something in there.

(think this should cover your question)

click All on the leftmost (or topmost) Facet.

thx guys,
this was the problem, had to turn it on: preferences > general > Always send to playlist.