
Sometimes a user needs extra context to decide what to enter — like checking what they've submitted before — but sending them to a whole new page loses their place. A Slideout opens a panel from the edge of the screen with that context, while the form stays visible underneath.
Attach an "Open Modal" action (slideout display mode) to a button. In this expense form, View Past Expenses opens a slideout instead of a new page.
Populate the slideout with real, relevant content. Here it lists the employee's three most recent approved expenses — date, description, amount, and status — so they can see their own submission history before deciding on a new one.

The user closes the slideout to return to the form, with the form's in-progress values untouched underneath.
The user gets the context they need to make a decision, without losing their place or their in-progress form data.