From FreeCAD Documentation
- There has to be a previous Tree view selection.
- There are several ways to invoke the command:
- Click on the black down arrow to the right of the button and select the Selection back option from the flyout. Note: the button image will change depending on the selected option.
- Select the View → TreeView actions → Selection back option from the menu.
- Use the keyboard shortcut: S then B.
- The previous selection is restored.