something wrong with dependencies is my guess. sugar-browse-activity is best used within the Sugar desktop, which is the sucrose package on Debian.
sugar-activity provided by python-sugar3 package does not work very well outside the Sugar user interface shell; just tried it then and huge traceback because python-carquinyol wasn't installed, but that's a recommends for python-jarabe so my mistake. python-carquinyol installed and the sugar-browse-activity starts up, but without any window manager decorations (in wmaker), because it is written to be used within the Sugar desktop, which is a fullscreen app design without windows. sugar-browse-activity does suggest python-jarabe for the user interface shell; perhaps it should require or recommend instead. upstream has some more details if you're interested, see http://www.sugarlabs.org/ http://wiki.sugarlabs.org/go/Debian not surprised forums didn't know, see also https://wiki.debian.org/Sugar