According to MSDN, responding to a UDN_DELTAPOS notification (sent by an "Up Down Control") with a non-zero value, will cause the control not to change value.

However, that doesn't seem to work for me. I wanted to use this to compare two up-downs and make sure the "Max" value is always >= the "Min" value. The comparason works, and I return TRUE, when I want to prevent update, but the control updates anyway.
Posted on 2002-10-20 18:19:59 by The Worrier King