The Workspace dialog in the Page tab lets you set an exact size for your work area and define what happens if your diagram would exceed this area.
In the Set the Workspace dialog, you'll see a preview of your document.
Infinite Canvas
By default, most templates are set to Autogrow. This means your canvas is infinite and will expand as you add new shapes and even other diagrams. By default, the work area will expand right and down.
Using this dialog, you can specify that your infinite canvas also grow towards the top and left.
Simply check the box that says "Allow the Work Area to grow to the top and left".
Set a Fixed Canvas Size
If your goal is to print your diagram, you can set your work area to a fixed size and specify either inches (for example a standard 8" x 11" page size with margins) or pages.
Note: SmartDraw will not let you set a fixed size smaller than what would fit any existing shapes in your work area.