It seems like sometimes the drop-down functionality is broken in Piwik 1.4:
E.g., in my dashboard I have the search-term widget and it looks like this (after expanding the options):
Keyword1 +--Google (links to Keyword2) Keyword2 +--No data to display
The same goes for the visitor country (GeoIP) widget:
Germany +--New York +--Washington D.C. USA +--No data to display
I just had this issue when I head only two entries in each widget.
Now there has been an additional visitor and everything works fine again…