The image shows the onBeforeExit action chain open in the Actions editor. The Structure view on the left shows Get Dirty Data Status, followed by If getDirtyDataStatusResult.status === 'dirty', then Fire Notification and Return.

The If action is selected to shows its properties on the canvas as well as in the Properties pane. The canvas shows the Fire Notification action with "summary: You have unsaved changes. Please Save or Cancel.", "displayMode: transient", and "type: error". The Return action shows payload as:

{
  cancelled: true,
}