WinApi - How to obtain SHELLDLL_DefView - c++

Question

I am trying to obtain handle to SHELLDLL_DefView.
So, I have this code.
HWND hProgman = FindWindow(L"Progman", NULL);
HWND hWnd = FindWindowEx(hProgman, 0, L"SHELLDLL_DefView", NULL);
Eveyrtihing works OK, until I change in Windows desktop brackground to slideshow. Then when I search with spy++ hierarchy of the windows, than SHELLDLL_DefView has another parent. Now it is #32769 (Desktop) -> WorkerW -> SHELLDLL_DefView. So I can't find it. Problem is that when I try
HWND desktop = GetDesktopWindow();
HWND hWnd = FindWindowEx(desktop , 0, L"WorkerW", NULL);
HWND hWnd = FindWindowEx(hWnd, 0, L"SHELLDLL_DefView", NULL);
Than SHELLDLL_DefView is not found. WorkerW yes.
Can anybody help?

Answer 1

Your code only works on some Windows versions as "SHELLDLL_DefView" can be found under "WorkerW" or "Progman" and as you discovered there can be many windows under the "WorkerW" class (normal in Win7).
Microsoft Docs report EnumWindows() is more reliable than calling GetWindow()/FindWindowEx() functions in loops, so more universal code (tested on Windows 98/Windows 7) would look like this (say you want to refresh the desktop):
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam) {
HWND hNextWin;
hNextWin = FindWindowExA(hwnd, 0, "SHELLDLL_DefView", 0);
if ( hNextWin ) {
// The correct desktop shell window under Progman/WorkerW will have only 1 child window!
if ( GetNextWindow(hNextWin, GW_HWNDNEXT) || GetNextWindow(hNextWin, GW_HWNDPREV) )
return true;
// We found correct handle
PostMessageA(hNextWin, WM_KEYDOWN, VK_F5, 0);
return false;
}
return true;
}
void main() {
EnumWindows(&EnumWindowsProc, 0);
}

Answer 2

I found the answer. Need to iterate through all WorkerW.
HWND destop = GetDesktopWindow();
HWND hWorkerW = NULL;
HWND hShellViewWin = NULL;
do
{
hWorkerW = FindWindowEx(destop, hWorkerW, L"WorkerW", NULL);
hShellViewWin = FindWindowEx(hWorkerW, 0, L"SHELLDLL_DefView", 0);
} while (hShellViewWin == NULL && hWorkerW != NULL);