fDrawCtrl1.Document.ActiveView.EnableMagnifierView = true;
fDrawCtrl1.Document.ActiveView.MagnifierSize = 400;
Magnifier view is usefull when user need to zoom in to certain portion of the drawing while maintaining the whole drawing. The user may use the method SetMagnifierScale to set the position and the magnifier scale of the magnifier view but remember to update the view with the command seeDrawCtrl.Document.Refresh.
Magnifier view should not be turn on when doing editing operation such as selecting objects or drawing any entities because it could slow down the editing operation.