The Axis menu item to open the tool editor works when Axis is first started, but typically only once. I have not figured out what is required to cause the error, ie at what point the menu item begins to be ignored.
The bug has existed for quite a long time. Launching tooledit from the command-line still works, however.
it is possible that this problem is related to ticket 329, which seems to hint at a problem with internationalisation.
Applying the patch suggested in #329, this is solved in my simulator and in a real machine using 2.6.0~pre. I did not tested in 2.5.3.
Cannot reproduce in v2.6.0-pre1-27-g2374e3e
I also cannot reproduce #329 (tooledit translates properly when I set LANG=de)
Please reopen if this is still a problem. I'm worried about it not consistently happening to you.