tvn-itemexpanding.md

title	description	ms.assetid	keywords	topic_type	api_name	api_location	api_type	ms.topic	ms.date
TVN_ITEMEXPANDING notification code (Commctrl.h)	Notifies a tree-view control's parent window that a parent item's list of child items is about to expand or collapse. This notification code is sent in the form of a WM\_NOTIFY message.	5ce256df-49e5-4fbf-9cdc-79dd2edbd8ec	TVN_ITEMEXPANDING notification code Windows Controls	apiref	TVN_ITEMEXPANDING TVN_ITEMEXPANDINGA TVN_ITEMEXPANDINGW	Commctrl.h	HeaderDef	reference	05/31/2018

TVN_ITEMEXPANDING notification code

Notifies a tree-view control's parent window that a parent item's list of child items is about to expand or collapse. This notification code is sent in the form of a WM_NOTIFY message.

TVN_ITEMEXPANDING 

    pnmtv = (LPNMTREEVIEW) lParam 

Parameters

lParam

Pointer to an NMTREEVIEW structure. The itemNew member is a TVITEM structure that contains valid information about the parent item in the hItem, state, and lParam members. The action member indicates whether the list is to expand or collapse. For a list of possible values, see the description of the TVM_EXPAND message.

Return value

Returns TRUE to prevent the list from expanding or collapsing.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Header	Commctrl.h
Unicode and ANSI names	TVN_ITEMEXPANDINGW (Unicode) and TVN_ITEMEXPANDINGA (ANSI)

See also

TVN_ITEMEXPANDED