Entry Page Filters

[LifeAtTheCircus]

If I click on the "Popular Pages" Link it brings up a nice summary and then I can drill down into any page in the list and apply a filter to those visitors (say, "visitor paths" or "came from"). This is a great feature. Why is it that no filter options are available with the "Entry page" and "Came From" lists? It would be great to see how many people that come from <fill in blank> stick around, come back, ect. Why are the filter option not available in these views?