TRichEdit右键滚屏代码[VC/C++编程]

void __fastcall TMainForm::RichEditMouseMove(TObject *Sender,TShiftState Shift, int X, int Y)
{
if(RightButtonFlag)
　 {
　 if(RightY>(Y+8))
　　 {
　　 RightY=Y;
　　 SendMessage(RichEdit->Handle, EM_SCROLL, SB_LINEDOWN, 0);
　　 }
　 else if(RightY<(Y-8))
　　 {
　　 RightY=Y;
　　 SendMessage(RichEdit->Handle, EM_SCROLL, SB_LINEUP, 0);
　　 }
　 RichEditDragFlag=true;
　 }
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::RichEditMouseDown(TObject *Sender,TMouseButton Button, TShiftState Shift, int X, int Y)
{
if(Button==mbRight)
　 {
　 RightButtonFlag=true;
　 Screen->Cursor=crHandPoint;
　 RightX=X;
　 RightY=Y;
　 SetCapture(RichEdit->Handle);
　 }
else
　 RightButtonFlag=false;
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::RichEditMouseUp(TObject *Sender,TMouseButton Button, TShiftState Shift, int X, int Y)
{
if(RightButtonFlag)
　 ReleaseCapture();
if(RichEditDragFlag)
　 {
　 RightButtonFlag=false;
　 RichEditDragFlag=false;
　 Screen->Cursor=crDefault;
　 RichEdit->PopupMenu=NULL;
　 }
else
　 {
　 RichEdit->PopupMenu=RichEditPopupMenu;
　 }
}