>I can see it as a temporary measure until you find better solution because it's extremely user unfriendly.
Well, in my POV, when a HTML page is being loaded, it shouldn't be interuptable. I mean, we could interrupt the process, but then, the browser should be smart enough to avoid any interaction with it.
For example, when a VFP form is loading in your application, you can't interrupt it. The same should follow here.
However, I understand that the browser could allow interruption in it because of slow connection and stuff like that, but the page should become unavailable.
So, those are issues we have to deal with.
Doing it at that level for now, only make that validation kicks in rarely. But, when it happens, it makes sure no save is done.