Qt Assistant current page not cleared on change of filter

In Qt assistant, say, A doc page is open and we change the filter to some filter that does not have the current page in it.
The currently displayed page which is not part of new filter, is not cleared, shouldn't it be cleared, may be back to home page?
Even “Go >> Sync with Table of Contents” is also not having any impact.

I am not sure about expected behavior, so raising this defect to get developer's viewpoint.