Use the Tree Overview
You can zoom in or out on the tree in a dedicated panel.
- 
			   Right-click an element in the 
				tree
				then select 
				Display > Tree
					 Overview (or press 
				Shift+F2).
			 
			 This displays the Overview on specifications panel containing a view of a tree's portion.
- 
			 Point to the overview dialog box to display the 
				 pointer, and drag.
			 
			 This drags the overview viewport through which you view part of the tree. pointer, and drag.
			 
			 This drags the overview viewport through which you view part of the tree.While dragging, the pointer changes to  . .
- 
			 Drag the handles located in the upper-right and lower-left
				corners of the viewport.
			 
			 This zooms the size of the overview viewport. Only that part of the tree that you see inside the overview viewport is visible in the document tab.