c++builder如何将容器中的组件坐标转化为相对空间相对与窗体的坐标

c++builder设计窗体时，用了个多页窗体PageControl，在PageControl中加了个Stringgrid1,我需要在stringgrid1的第二列加上combobox，但是怎么设置坐标运行结果都错，我是拿stringgrid1的屏幕坐标减去窗体的屏幕坐标在加上单元格相对于stringgrid1的位置，但是运行的位置总是不对，拜托各位大神帮个忙，我这一直弄不出来，下面工作没法继续！刚注册的账号，只有5个c币

  z=new TComboBox*[StringGrid1->RowCount-1];
          for(int i=0;i< StringGrid1->RowCount-1;i++) 
          {
                TRect   rect   =   StringGrid1->CellRect(1,  i+1);//CellRect：返回第二列单元格的Rect对象，相对于stringgrid的坐标
                z[i]=new TComboBox(this->StringGrid1);  //
                int X;
                int Y;

                TPoint *pt= new TPoint;
               TPoint *pt1= new TPoint;
               TPoint *pt2= new TPoint;
               pt2->x=FunctionDefine->Left; //窗体的屏幕坐标
               pt2->y=FunctionDefine->Top;
               //Edit7->Text= pt2->x;
               //Edit8->Text= pt2->y;

              //Edit1->Text=StringGrid1->Left; //获得客户区坐标
               //Edit2->Text=StringGrid1->Top;
               pt->x=StringGrid1->Left;
               pt->y=StringGrid1->Top;
               *pt1=ClientToScreen(pt);//stringgrid的屏幕坐标
              // *pt1=ClientToScreen(hwnd,*pt);//stringgrid1的屏幕坐标
                X=pt1->x-pt2->x;
                Y=pt1->y-pt2->y;

                z[i]->SetBounds(rect.Left+1+X,   rect.Top+1+Y,   rect.Width()+1,   rect.Height()+1) ;
                z[i]->Parent=this;
                z[i]->AddItem("布尔",this);
                z[i]->AddItem("模拟",this);
                z[i]->ItemIndex=0;
                z[i]->Show();
         }

combobox 放在哪个容器上面就按这个容器的客户坐标算。
无论如何都不会用到屏幕坐标啊！

直接用ClientToScreen API转换
http://blog.chinaunix.net/uid-14607221-id-2794661.html

我需要在程序中生成这个combobox啊,用setbounds的话不是得需要这个combobox的相对窗体的坐标吗？就是这个坐标得不到啊

代码是这个样子的：

TForm1 Form1;
TList ComboBoxList;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
ComboBoxList = new TList();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject Sender)
{
for (int i = 0; i < ComboBoxList->Count; i++)
{
delete (TComboBox)(ComboBoxList->Items[i]);
}
delete ComboBoxList;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::StringGrid1DrawCell(TObject Sender, int ACol, int ARow, TRect &Rect,
TGridDrawState State)
{
TComboBox ComboBoxItem;
TPoint OrgPoint, TempPoint, NewPoint;

if(ARow >= 1 && ACol == 1)
{
ComboBoxItem = new TComboBox(Form1);
ComboBoxItem->Tag = ARow;
OrgPoint.x = Rect.Left;
OrgPoint.y = Rect.Top;

TempPoint = ((TStringGrid*)Sender)->ClientToScreen(OrgPoint);
NewPoint = ScreenToClient(TempPoint);
ComboBoxItem->SetBounds(
  Rect.Left + ((TStringGrid*)Sender)->GridLineWidth*2
  ,
  ((TStringGrid*)Sender)->Top + NewPoint.y
  ,
  Rect.Right - Rect.Left
  ,
  Rect.Bottom - Rect.Top
);
InsertControl(ComboBoxItem);

ComboBoxList->Add(ComboBoxItem);

}
}