To zoom in on the page in the editor, hold the space bar on your keyboard, then dial the mouse wheel up to increase the zoom of your page. To zoom out, hold the space bar on your keyboard, then dial the mouse wheel down.
To move the canvas to a new position, hold the space bar down, click down on the page, then drag the mouse. Your canvas will pan over to the direction of your mouse movement.
To reset to the default full-screen view, click on the Reset button over the canvas. This button will only appear if the canvas is displayed outside the default 100% view.
Note that Undo/Redo or changing pages will reset the canvas position to the default full screen view.