Plugin dialog won't update without restart

I’m trying to make a “Editor toolbar button”-plugin from the template. But when I try to update the dialog text I need to restart the editor to make it display the new message. And I get this message each time I try to reload/unload the module:

Module being reloaded does not support dynamic unloading – abandoning existing loaded module so that we can load the recompiled version!

Any one got a clue around this problem?

I have the same issue with my modules, impossible to update without a restart of the Editor… It is quite inconvenient.