Can't change the background color of windows which are inside another window - c++

Question

I want to change the background color of a STATIC window, both - on load and change it on runtime. So far I have been able to change the color the following way:
case WM_CTLCOLORSTATIC:
{
HDC hdcStatic = (HDC)wParam;
SetTextColor(hdcStatic, RGB(200, 200, 20));
SetBkColor(hdcStatic, RGB(10, 10, 10));
SetBkMode(hdcStatic, TRANSPARENT);
return (INT_PTR)CreateSolidBrush(RGB(30, 30, 30));
}
Everything works fine and the background color gets changed, except for any STATIC windows, which are inside another static window:
HWND mainContainer = CreateWindowEx
(
0,
_TEXT("STATIC"),
"",
WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_SOLID,
10, 10, 500, 500,
hwnd,
NULL,
(HINSTANCE)GetWindowLong(hwnd, GWLP_HINSTANCE),
NULL
);
HWND subItem = CreateWindowEx
(
0,
_TEXT("STATIC"),
"SubItem",
WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_SOLID,
10, 10, 100, 100,
mainContainer,
NULL,
(HINSTANCE)GetWindowLong(mainContainer, GWLP_HINSTANCE),
NULL
);
In this case the mainContainer color gets changed, but not the background color for subItem. Any ideas why this is happening? Thank you!

Answer 1

The message WM_CTLCOLORSTATIC will be sent only to the parent window, but not parent's parent window.
According to About Static Controls :
The window procedure for the predefined static control window class
performs default processing for all messages that the static control
procedure does not process.
The WM_CTLCOLORSTATIC is not in the list that it process. So The predefined window procedure will passes the message to DefWindowProc for default processing.
(We really don't often put a static window inside another static window. This is not a common operation. So you should reset the parent window of subItem to hwnd.)