TVN_ITEMEXPANDING

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 message is sent in the form of a WM_NOTIFY message.

TVN_ITEMEXPANDING 
    pnmtv = (LPNMTREEVIEW) lParam 

Parameters

pnmtv

Address of 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 Values

Returns TRUE to prevent the list from expanding or collapsing.

Requirements

  Windows NT/2000: Requires Windows NT 3.51 or later
  Windows 95/98: Requires Windows 95 or later
  Header: Declared in commctrl.h.