By default, the ZoomStep property is 10.  the ZoomMin, ZoomMax and ZoomStep determines the range of the zooming to be used, if the ZoomLevels property is empty. Use the ToolBarFormat property to customize the control's toolbar. The ZoomLevels property specifies the zooming factors to be displayed on the control's toolbar.  The Zoom property specifies the surface's current zooming factor. The AllowZoomSurface property specifies the combination of keys that allows the user to magnify or shrink the surface. The AllowZoomWheelSurface property specifies whether the user can zoom the surface by rotating the mouse wheel. The control fires the LayoutStartChanging(exSurfaceZoom) / LayoutEndChanging(exSurfaceZoom) event when the user zooms the surface.