Using foobar v0.8.2, W2K+SP4, S3 Trio 3D/2X
Everytime I use from menu Playback->Order and choose a value out of the four ones, a white vertical line appears to the left of "Foobar" menu item
You can see that here:

This doesn't happen if I choose the value that is currently selected, only if I choose one of the rest.
EDIT: I use "Lock the toolbars" and it seems that this line appears in place of the grey vertical slider that exists to the left of "Foobar" menu item when "Lock the toolbars" is not selected.