To limit the length of text that can be entered when editing an item label,
you have to add a handler for the TVN_BEGINLABELEDIT notification. Within
this handler get the edit control and call the LimitText() function.
void COutline::OnBeginLabelEdit(NMHDR* pNMHDR, LRESULT* pResult)
{
TV_DISPINFO* pTVDispInfo = (TV_DISPINFO*)pNMHDR;
// Limit text to 127 characters
GetEditControl()->LimitText(127);*pResult = 0;
}