[Bug 54453] New: Wow64 UI Drawing Black Screen When WNDCLASSEXW::hbrBackground set to NULL

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54453

Bug ID: 54453
           Summary: Wow64 UI Drawing Black Screen When
                    WNDCLASSEXW::hbrBackground set to NULL
           Product: Wine
           Version: 8.1
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: win32u
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

If set WNDCLASSEXW::hbrBackground to 0 (Default hbrBackground), Black Screen
Occur
For Example, The Simple Window:

#include <Windows.h>
#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;                                // current instance
WCHAR szTitle[MAX_LOADSTRING] = L"HELLO";                  // The title bar
text
WCHAR szWindowClass[MAX_LOADSTRING] = L"HELLO";            // the main window
class name

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);

int main(void)
{
    HINSTANCE hInstance = GetModuleHandle(NULL);
    int nCmdShow = SW_SHOW;

// TODO: Place code here.

// Initialize global strings
    MyRegisterClass(hInstance);

// Perform application initialization:
    if (!InitInstance(hInstance, nCmdShow))
    {
        return FALSE;
    }

MSG msg;

// Main message loop:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, NULL, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

return (int)msg.wParam;
}

//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

wcex.cbSize = sizeof(WNDCLASSEX);

wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = NULL;
    wcex.hCursor = NULL;
    wcex.hbrBackground = (HBRUSH)NULL; // Black Screen Occur!
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = NULL;
    return RegisterClassExW(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable
and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    hInst = hInstance; // Store instance handle in our global variable

HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance,
nullptr);

if (!hWnd)
    {
        return FALSE;
    }

ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

return TRUE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
    {
        int wmId = LOWORD(wParam);
        // Parse the menu selections:
        switch (wmId)
        {
        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
        }
    }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}