I am using the latest (qucs-0.0.19-OSX10.7.pkg) package downloaded from SourceForge on OSX 10.8.5. When I try to select the Cartesian chart or the Polar chart (at least) the application crashes (and pops up the crash reporter for OSX).
I tried placing the fgummel.sch file in ~/.ducs/examples_prj and it crashes when I tried to load it.
Let me know if I can provide any more details.