case WM_MOUSEMOVE:
      MousePt.X = (GLfloat)LOWORD(lParam);
      MousePt.Y = (GLfloat)HIWORD(lParam);
      isClicked   = (LOWORD(wParam) & MK_LBUTTON) ? true : false;
      isRClicked  = (LOWORD(wParam) & MK_RBUTTON) ? true : false;
    case WM_LBUTTONUP:
      isClicked = false;
      break;
    case WM_RBUTTONUP:
      isRClicked = false;
      break;
    case WM_LBUTTONDOWN:
      isClicked = true;
      break;
    case WM_RBUTTONDOWN:
      isRClicked = true;
      break;