You can create a boundary around the selected objects by pressing Shift and double-clicking the Rectangle tool. This feature can also be accessed by clicking Arrange > Shaping > Boundary.
Tip provided by Pratik Shah, CorelDRAW Master, Graphic Designer & Trainer.
Note: This tip is available in 3 languages (English, French and German).
Shift doubleclick on the rectangle tool does create a bounding rectangle as described.. Arrange-Shaping-Boundary creates an outline curve, not at all the same unless the selected object is a single rectangle.