UDN_DELTAPOS
The operating
system sends the UDN_DELTAPOS notification message to the parent window of an
up-down control when the position of the control is about to change. This
happens when the user requests a change in the value by pressing the control s
up or down arrow. The UDN_DELTAPOS message is sent before the WM_VSCROLL or WM_HSCROLL message that actually changes
the control s position. This lets you examine, allow, modify, or disallow the
change. The UDN_DELTAPOS message is sent in the form of a WM_NOTIFY message.
UDN_DELTAPOS
pnmud = (NM_UPDOWN FAR *) lParam
Parameters
pnmud
Pointer to an
NM_UPDOWN
structure that contains information about the position change.
The iPos member of this structure contains the current position
of the control.
The iDelta member of the structure is a signed integer that
contains the proposed change in position. If the user has clicked on the up
button, this is a positive value. If the user has clicked on the down button,
this is a negative value.
Return Values
Return TRUE
in response to this message to prevent the change in the control s position.
Return FALSE
to allow the change in the control s position.
See Also