Select the Zoom in button from the Zoom combo box on the General Toolbar and click on it as many times as necessary.
Select the Zoom out button from the Zoom combo box on the General Toolbar and click on it as many times as necessary.
Scroll the mouse wheel over the canvas.
Click the Zoom all button on the General Toolbar to optimize the size of the structure to the canvas size.
Select the Zoom to selection button from the Zoom combo box on the General Toolbar to display only the selected structure on the canvas .
Appears when needed: when the structure is bigger than the canvas or when some structural parts are out of the canvas.