Searching after selecting text should select "Selection in Current Document or Panel" automatically
If you select a text and press Ctrl-F or Ctrl-H to reach the Search dialog it could be set that "Look in:" points to "Selection in Current Document or Panel" since this is what you usually want to do....
Better behaviour would be to automatically select Selection in Current Document or Panel, that is what I am trying to say. Please add this as enhancement to your bug database.