Write an OnChangingEx event handler to conditionally disallow changes to the value of Position. Set the AllowChange parameter to false to prevent a change to the current value of Position. 

Sender is the up-down control that received the event. This may be in response to a user click on the arrow buttons or an attempt to change the value of Position programmatically. 

AllowChange returns a value that indicates whether the change is permitted. 

NewValue indicates the new value of Position if the change is allowed. 

Direction indicates whether the value of Position is to be increased or decreased. 

CanChange 

Position 

OnChanging