Sending message TVM_EDITLABEL fails - winapi

Question

TreeView_EditLabel(tv, item) fails(returns zero).
item is valid, and is the only item in the treeview.
What's the problem? Is there some prerequisite? Or it just doesn't work?
I'm on Windows 10.
Here's a minimal reproducible example
#include <windowsx.h>
#include <CommCtrl.h>
#include <assert.h>
#pragma comment(lib, "Comctl32.lib")
HWND hTv;
HTREEITEM hItem;
auto className = L"someclass";
ATOM MyRegisterClass(HINSTANCE hInstance);
void InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow)
{
InitCommonControls();
MyRegisterClass(hInstance);
InitInstance(hInstance, nCmdShow);
MSG msg;
while (GetMessage(&msg, nullptr, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;
}
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW wcex{};
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.lpszClassName = className;
return RegisterClassExW(&wcex);
}
void InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HWND hWnd = CreateWindowW(className, L"", WS_OVERLAPPEDWINDOW, 400, 400, 400, 400, nullptr, nullptr, hInstance, nullptr);
assert(hWnd);
hTv = CreateWindowW(WC_TREEVIEW, L"Tree View", WS_VISIBLE | WS_CHILD | WS_BORDER | TVS_HASLINES, 0, 0, 300, 300, hWnd, 0, 0, NULL);
assert(hTv);
{
TVITEM tvi{};
TVINSERTSTRUCT tvins{};
tvi.mask = TVIF_TEXT;
wchar_t name[] = L"item";
tvi.pszText = name;
tvins.item = tvi;
hItem = TreeView_InsertItem(hTv, &tvins);
}
ShowWindow(hWnd, nCmdShow);
SetFocus(hTv);
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_NOTIFY:
{
switch (reinterpret_cast<LPNMHDR>(lParam)->code)
{
case NM_CLICK:
assert(TreeView_EditLabel(hTv, hItem));
break;
}
break;
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}

Answer 1

A tree-view control needs the TVS_EDITLABELS control style set to support editing labels of tree-view items.
You need to replace the tree-view control creation code
hTv = CreateWindowW(
WC_TREEVIEW,
L"Tree View",
WS_VISIBLE | WS_CHILD | WS_BORDER | TVS_HASLINES,
0, 0, 300, 300,
hWnd,
0,
0,
NULL);
with this:
hTv = CreateWindowW(
WC_TREEVIEW,
L"Tree View",
WS_VISIBLE | WS_CHILD | WS_BORDER | TVS_HASLINES | TVS_EDITLABELS,
0, 0, 300, 300,
hWnd,
0,
0,
NULL);
The tree-view controls overview overview provides additional details under the section titled tree-view label edition.