could you please try to set this:
and then start /usr/bin/freeplane from the same console?
You may also want to try OpenJDK7, users have reported several problems
with OpenJDK6. This is much more likely a JDK than a Freeplane issue.
Finally, 1.2.23 is in testing (but in order to be able to
compile/install it on wheezy, you also need libjgoodies-forms-java 1.6).
This is the maintainer address of Debian's Java team
debian-j...@lists.debian.org for discussions and questions.