>>I still can click on any tab and interrupt loading process. Doesn't look like the lock is working.
>
>The safe checkup is done at the Save level for now in order to advise the user that the save can't be processed because the form was not loaded completely. That's the initial approach. Detecting that at every click on the form is something much different and probably overkill for that verification.

I can see it as a temporary measure until you find better solution because it's extremely user unfriendly.