Cursor and Window position problem

[Valerianel]

I'm trying to create 2 windows and magnet them so they stay close to each other by 10px: the main window and bottom window. The bottom window act as a resizer for main window when user drag it.
Everything is fine with one problem: when main window is moved, the cursor points are not correct anymore. I posted below the pseudo code and a screenshot to show the effect problem.

hwndMain = CreateWindow(L"classMain", L"main", WS_POPUP, 50, 0, 800, 600, NULL, NULL, instanceMain, NULL);
hwndResizer = CreateWindowEx(WS_EX_LAYERED, TEXT("classResizer"), L"", WS_POPUP, 400, 610, 55, 35, hwndMain, NULL, instanceMain, NULL);

resizer proc

case WM_LBUTTONUP: {
		ReleaseCapture();
	} break;

	case WM_LBUTTONDOWN: {
		SetCapture(hwndBottomResizer);
	} break;

	case WM_MOUSEMOVE: {

		if (wParam & MK_LBUTTON) {

			RECT bottomResizerRect, mainWindowRect;
			POINT posBottomResizer;
			
			GetWindowRect(hwndBottomResizer, &bottomResizerRect);
			GetWindowRect(hwndMain, &mainWindowRect);

			posBottomResizer.x = GET_X_LPARAM(lParam); //(int)(short)LOWORD(lParam);
			posBottomResizer.y = GET_Y_LPARAM(lParam); //(int)(short)HIWORD(lParam);
			ClientToScreen(hwndBottomResizer, &posBottomResizer);

			HDWP move = BeginDeferWindowPos(2);
			DeferWindowPos(move, hwndMain, 0, mainWindowRect.left, mainWindowRect.top, mainWindowRect.right - mainWindowRect.left, posBottomResizer.y, 0);
			DeferWindowPos(move, hwndBottomResizer, 0, bottomResizerRect.left, posBottomResizer.y + 10, bottomResizerRect.right - bottomResizerRect.left, 35, 0);
			EndDeferWindowPos(move);

		}

	} break;

main proc

	case WM_NCHITTEST: {

		moveWindows = DefWindowProc(hwnd, message, wParam, lParam);

		RECT rc, brc;

		GetWindowRect(hwnd, &rc);
		GetWindowRect(hwndBottomResizer, &brc);

		POINT pt;
		pt.x = GET_X_LPARAM(lParam);
		pt.y = GET_Y_LPARAM(lParam);
		ScreenToClient(hwnd, &pt);

		HDWP move = BeginDeferWindowPos(1);
		//DeferWindowPos(move, hwndMain, 0, mainWindowRect.left, mainWindowRect.top, mainWindowRect.right - mainWindowRect.left, posBottomResizer.y, 0);
		DeferWindowPos(move, hwndBottomResizer, 0, brc.left, rc.bottom + 10, brc.right - brc.left, 35, 0);
		EndDeferWindowPos(move);

		if (moveWindows == HTCLIENT) {
			return HTCAPTION;
		}
		else {
			return moveWindows;
		}
	} break;

See below gif for effect problem.

[Valerianel]

Please watch this gif to see how the main window rect is losing control after is moved by bottom resizer
https://ibb.co/TtTVZSM

[2kaud]

[Thread moved]

[VictorN]

Please watch this gif to see how the main window rect is losing control after is moved by bottom resizer
https://ibb.co/TtTVZSM

Unfortunately it is not clear what you are doing and what for...
Could you explain it in more details?

[Valerianel]

I want to create a smaller window below main window to act as a resizer button. The problem is that when the main window is moved, the smaller window below it is not sending correct resize position anymore (like in gif animation). I guess this is because once the main window is moved the other window is not getting correct GetWindowRect positions for some reason

[2kaud]

I guess this is because once the main window is moved the other window is not getting correct GetWindowRect positions for some reason

Never guess with Windows programming! Do some debugging and find out. Determine what info you are getting and if not as expected, then understand what you are getting.