Example of creating a window using a private api on a dll-injected immersive process

main.cpp

#include "pch.h"
#pragma comment(lib, "gdi32.lib")

enum ZBID
{
	ZBID_DEFAULT = 0,
	ZBID_DESKTOP = 1,
	ZBID_UIACCESS = 2,
	ZBID_IMMERSIVE_IHM = 3,
	ZBID_IMMERSIVE_NOTIFICATION = 4,
	ZBID_IMMERSIVE_APPCHROME = 5,
	ZBID_IMMERSIVE_MOGO = 6,
	ZBID_IMMERSIVE_EDGY = 7,
	ZBID_IMMERSIVE_INACTIVEMOBODY = 8,
	ZBID_IMMERSIVE_INACTIVEDOCK = 9,
	ZBID_IMMERSIVE_ACTIVEMOBODY = 10,
	ZBID_IMMERSIVE_ACTIVEDOCK = 11,
	ZBID_IMMERSIVE_BACKGROUND = 12,
	ZBID_IMMERSIVE_SEARCH = 13,
	ZBID_GENUINE_WINDOWS = 14,
	ZBID_IMMERSIVE_RESTRICTED = 15,
	ZBID_SYSTEM_TOOLS = 16,
	ZBID_LOCK = 17,
	ZBID_ABOVELOCK_UX = 18,
};

LRESULT CALLBACK TrashParentWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
	case WM_CREATE:
		break;

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	case WM_WINDOWPOSCHANGING:
		return 0;
	case WM_CLOSE:
		HANDLE myself;
		myself = OpenProcess(PROCESS_ALL_ACCESS, false, GetCurrentProcessId());
		TerminateProcess(myself, 0);

		return true;

		break;

	default:
		break;
	}

	return DefWindowProc(hwnd, message, wParam, lParam);
}

HWND hwnd = NULL;
typedef HWND(WINAPI* CreateWindowInBand)(_In_ DWORD dwExStyle, _In_opt_ ATOM atom, _In_opt_ LPCWSTR lpWindowName, _In_ DWORD dwStyle, _In_ int X, _In_ int Y, _In_ int nWidth, _In_ int nHeight, _In_opt_ HWND hWndParent, _In_opt_ HMENU hMenu, _In_opt_ HINSTANCE hInstance, _In_opt_ LPVOID lpParam, DWORD band);

void CreateWin(HMODULE hModule, UINT zbid, const wchar_t* title, const wchar_t* classname)
{
	{
		HINSTANCE hInstance = hModule;

		WNDCLASSEX wndParentClass = {};
		wndParentClass.cbSize = sizeof(WNDCLASSEX);
		
		wndParentClass.cbClsExtra = 0;
		wndParentClass.hIcon = NULL;
		wndParentClass.lpszMenuName = NULL;
		wndParentClass.hIconSm = NULL;
		wndParentClass.lpfnWndProc = TrashParentWndProc;
		wndParentClass.hInstance = hInstance;
		wndParentClass.style = CS_HREDRAW | CS_VREDRAW;
		wndParentClass.hCursor = LoadCursor(0, IDC_ARROW);
		wndParentClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
		wndParentClass.lpszClassName = classname;
		
		auto res = RegisterClassEx(&wndParentClass);

		const auto hpath = LoadLibrary(L"user32.dll");
		const auto pCreateWindowInBand = CreateWindowInBand(GetProcAddress(hpath, "CreateWindowInBand"));

    		auto hwndParent = pCreateWindowInBand(WS_EX_TOPMOST | WS_EX_NOACTIVATE,
			res,
			NULL,
			0x80000000,
			0, 0, 0, 0,
			NULL,
			NULL,
			wndParentClass.hInstance,
			LPVOID(res),
			zbid);

    		SetWindowLong(hwndParent, GWL_STYLE, 0);
		SetWindowLong(hwndParent, GWL_EXSTYLE, 0);

		SetWindowPos(hwndParent, nullptr, 40, 40, 600, 600, SWP_SHOWWINDOW | SWP_NOZORDER);
		ShowWindow(hwndParent, SW_SHOW);
		UpdateWindow(hwndParent);

		if (hwndParent != nullptr)
			hwnd = hwndParent;
	}
}

DWORD WINAPI Thrd(LPVOID lpParam)
{
	CreateWin(NULL, ZBID_SYSTEM_TOOLS, L"Really Genuine Window++", L"TestPlus");

	MSG msg;
	while (GetMessage(&msg, nullptr, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return 0;
}

BOOL APIENTRY DllMain(HMODULE hModule,
					  DWORD  ul_reason_for_call,
					  LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		CreateThread(nullptr, 0, Thrd, hModule, NULL, NULL);
	break;
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		break;
	}

	return TRUE;
}

Anyway, how did you figure about this? Did you need it for some project, or...?
Also, do you happen to know of any hidden API or stuff like that than can hide buttons on the taskbar for UWP apps. The ITaskBarList interfaces (specifically DeleteTab()) work for regular apps, but not for UWP. Do you have any insight on this?
Thank you.

Nice Work! Can this be used in a c# app?