Here are three tips to help manage screen real estate on the Metadevice Editor's canvas:
Selecting Collapse from an object's pop-up menu enables you to fit more objects onto the canvas.
Selecting Clean Up Canvas from the Edit menu is useful when you have lots of objects on the canvas, and you are putting some of them away, or you are repositioning objects with the mouse. The Clean Up Canvas option rearranges objects on the canvas in a grid, making viewing easier.
Use the sash to resize the canvas. You can widen the canvas area by clicking the sash at the bottom of the Metadevice Editor window and dragging to the right.