If a page was previosuly populated with a different pkey, the old data will be visible when we switch to it.

The switch logic instead should be:

If the pkey hasn't changed, do not reload the data.
If the pkey has changed, clear the page before showing it, then load the data.

Thus, each widget needs a 'clear' method that can be called prior to making the page visibile.

Note that for the search pages, the filter/offset replaces the primary key, but the logic is the same.