Datetime picker updown support

[Duane Clark]

Rob Shearman wrote:
> 
> This seems really wrong. You are destroying and creating the updown 
> control on every size event?!?! That's really going to slow resizes 
> down. Is there any evidence that the native version does it like this?
> 

No, I don't have evidence of that. On the other hand, it is unlikely the 
control will ever be resized, except once after creation. Looking 
through the messages that the updown control responds to, there are none 
that allow resizing that I can see. And while I have not verified this 
with Microsoft docs, it supposedly implements all documented functions 
(according to the header).