Java-Editor in Eclipse M5 does not work when JBoss-IDE inst.

SourceForge Submitter: domic .
I installed jbosside1.0a_06.zip over M5 eclipse. From
now on the Java Editor did not work. Already open
editor windows showed a red "An error has occured when
creating this editor" and an attempt to open a new one
led to the error alert box "Unable to create part:
foo.java".

Uninstalling the plugin removed that problem too but
from now on the editor font was reset to the default
system font and the preferences for Java Editor Font
under Workbench/Fonts/ (not Java/Editor any more in M5)
to set the font size was missing. Re-installing M5 in
the same directory (preserving the other plugins)
solved the problem.