Despite the fact that I'm not running on Debian, I encountered this very bug and indeed I can confirm that it seems to be related to multiple screens.
However, I don't have to actually disable the secondary screen, it's enough to move the mouse to the primary one, so that the window is initially opend in the primary screen, which makes sweethome3d start up nicely. __ This is the maintainer address of Debian's Java team <http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-java-maintainers>. Please use debian-j...@lists.debian.org for discussions and questions.
