Holding Shift or Ctrl While Creating Rectangles and Ovals

• Hold Shift and drag to constrain a rectangle or an oval to a square or circle.
• Hold Ctrl (command in Macintosh) and drag to draw a rectangle or an oval from its center.

  Drag while holding Shift.

  Drag while holding Ctrl (command in Macintosh).

  The Ctrl and Shift keys can be used at the same time.