A few versions back FileMaker gained the ability to remember the current tab panel you were on when you switched from Browse to Layout mode
all the current active sliders / and tab panels are preserved.
When going from layout back to browse there needs to be a way to return to this exact state (menu bars/slide & tab panels) and prevent any triggers from running.
When you have many nested objects such as slide panels and or tab panels and now button bars switching between layout and browse mode there are conditions and triggers that fire off based on context and restoring every panel can be tedious just to get back to the desired view.
Having a separate window open on the same layout ( one in layout and one in browse ) does not work as soon as you save the layout the window in browse mode is restored to default menubar/tab/slider positions.
This also can be disruptive to any other users in the system during a data entry operation, as saving the window affects all users in that layout.