[...] 6_u37 was released by Apple with the Developer Package release in October of 2012. I wouldn't call that 'pretty old'.
At an age when Apple and its fanboys overexagerrate any security hole in Java because Apple took their time to fix a known hole a year ago, that revealed to be used in the very first virus under Mac OS X, it's an eternity! OS X will install 6_u43
See, you already missed one. Java 6 release version is now 6_u45! 
Can you recommend running it w/ Java 7 on OS X?
Don't try Java 7 with Sweet Home 3D yet, it's still too buggy as I reported at the end of the blog article about version 4. Seriously, Oracle released a Mac OS X version of the JDK too early.But since you seem to be able to use the Terminal, please try this:
- download Jar executable version of Sweet Home 3D
- run the program with the command:
java -Xmx1024m -jar /path/to/SweetHome3D-4.0.jar- if it still fails, some Java log starting by "Exception in thread" should appear in the Terminal window. Please report it here.
Thanks for your patience.
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Emmanuel Puybaret, Sweet Home 3D creator
