如何在裸机移植UCGUI时通过按键调处子子窗口？

我想通过桌面窗口上的两个按钮，分别调出两个不一样的子窗口，但是不知道应该在什么地方添加这样子窗口创建函数？应该在按钮的CALLBACK函数中吗？如果还想在子窗口中绘制一些控件，又应该在哪里添加？[C] 纯文本查看 复制代码
void BUTTON_Callback(WM_MESSAGE *pMsg) {  BUTTON_Handle hObj = pMsg->hWin;  BUTTON_Obj* pObj = BUTTON_H2P(hObj);  /* Let widget handle the standard messages */  if (WIDGET_HandleActive(hObj, pMsg) == 0)   {    return;  }  switch (pMsg->MsgId)   {#if BUTTON_REACT_ON_LEVEL  case WM_PID_STATE_CHANGED:    _OnPidStateChange(hObj, pObj, pMsg);    return;      /* Message handled. Do not call WM_DefaultProc, because the window may have been destroyed */#endif  case WM_TOUCH:    _OnTouch(hObj, pObj, pMsg);    return;      /* Message handled. Do not call WM_DefaultProc, because the window may have been destroyed */  case WM_PAINT:    GUI_DEBUG_LOG("BUTTON: _BUTTON_Callback(WM_PAINT)n");    _Paint(pObj, hObj);    return;  case WM_DELETE:    GUI_DEBUG_LOG("BUTTON: _BUTTON_Callback(WM_DELETE)n");    _Delete(pObj);    break;       /* No return here ... WM_DefaultProc needs to be called */  #if 0     /* TBD: Button should react to space & Enter */  case WM_KEY:    {      int PressedCnt = ((WM_KEY_INFO*)(pMsg->Data.p))->PressedCnt;      int Key        = ((WM_KEY_INFO*)(pMsg->Data.p))->Key;   switch (Key) {    case GUI_KEY_ENTER:      if (PressedCnt > 0)   {        _OnButtonPressed(hObj, pObj);       _OnButtonReleased(hObj, pObj, WM_NOTIFICATION_RELEASED);        return;      }      break;    case GUI_KEY_SPACE:      if (PressedCnt > 0)   {        _OnButtonPressed(hObj, pObj);      }   else   {        _OnButtonReleased(hObj, pObj, WM_NOTIFICATION_RELEASED);      }      return;}    break;}  #endif  }  WM_DefaultProc(pMsg);}