The DotNetSearchResultsPageView (way down in IdeaBlade.Cab.DotNet) uses a System.Windows.Forms.SplitContainer to hold the SmartPartPlaceholders for the SearcherView (top portion) and SearchResultsView (bottom portion).
The view attempts to adjust the splitter to the preferred height of the SearcherView when initially displayed, but as the window is resized, the split container attempts to maintain the same proportion between the top and bottom panels.
The minimum size for the top panel is set to 25 - smaller than the height of your searcher view.
There is a splitter between the searcher and search results views that you can use to expand the top searcher view and get rid of the scrollbar.
The SplitContainer has properties to control its behavior, but these are all hard-coded into the DotNetSearchResultsView, so your only choice would be to replicate that view in your foundation module and adjust it accordingly.
Hope this at least explains what's going on.
Bill J.