TRichEdit右键滚屏代码

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;
　}
}