Can't comment on FMP12, but what you are seeing is also present in FMP11. That is the only version that I have direct experience with. In my case, the IWP dB is not exposed to the public.
Therefore, I provided buttons for all navigation and the training/user guide for the dB explicitly says to not touch the regular browser buttons for navigation.
In circumstances where I thought it was likely that the user would use the back button, I created a new virtual window. Example is where the user is in a list view and clicks to show the detail of that record. Instead of switching directly to the Detail layout, I did a new window (virtual), found that one record, and went to the detail layout. My "Back" button then closed the window thus restoring the user to the list view layout.
I would imagine that the ultimate answer to your question would be to do your solution in Custom Web Publishing using PHP. This wasn't an option in my case, thus using IWP. My solution does not contain any sensitive data as yours does.