I have set my Java Compiler to jdk 1.5, the JVM 1.5.0 (OS X default) is the only jre checked at "Installed JRE's", and under "Execution Environment" the JavaSE-1.6 has no compatible JRE visible while J2SE-1.5 have the JVM 1.5.0 checked.
Yet, when I make a new Spring Roo project STS will instruct Roo to make the project with the option "-java 6" and in the properties STS have set project specific settings to jdk 1.6.
It works like this up until that I go into the settings and redo the same changes again (unchecking and rechecking for instance). Only then is my jdk settings respected.
As the process to reset the project in a working form, I regard this as a major inconvenience.