If Northwoods.GoXam.Diagram.AllowScroll is true, turning the mouse wheel causes the diagram to scroll up or down. If IsShiftKeyDown is also true, the diagram scrolls left or right.

If IsControlKeyDown is true and if Northwoods.GoXam.Diagram.AllowZoom is true, turning the mouse wheel changes the diagram's scale, zooming in or out while trying to keep the point in the model at the same point as the mouse.

Reference

DiagramTool Class
DiagramTool Members