关于拖放控件的问题 ( 积分: 100 )

在窗体中设置button的dragmode为dmAutomatic，可以实现拖放功能，但是无法响应onclick事件，设置dragmode为dmManual就可以相应onclick事件，但是拖放功能就无法实现。我想两种事件都相应，该怎么做呀，郁闷，求高手指点！

delphi源码
procedure TControl.WndProc(var Message: TMessage);
var
Form: TCustomForm;
KeyState: TKeyboardState;
WheelMsg: TCMMouseWheel;
begin
if (csDesigning in ComponentState) then
begin
Form := GetParentForm(Self);
if (Form <> nil) and (Form.Designer <> nil) and
Form.Designer.IsDesignMsg(Self, Message) then Exit
end;
if (Message.Msg >= WM_KEYFIRST) and (Message.Msg <= WM_KEYLAST) then
begin
Form := GetParentForm(Self);
if (Form <> nil) and Form.WantChildKey(Self, Message) then Exit;
end
else if (Message.Msg >= WM_MOUSEFIRST) and (Message.Msg <= WM_MOUSELAST) then
begin
if not (csDoubleClicks in ControlStyle) then
case Message.Msg of
WM_LBUTTONDBLCLK, WM_RBUTTONDBLCLK, WM_MBUTTONDBLCLK:
Dec(Message.Msg, WM_LBUTTONDBLCLK - WM_LBUTTONDOWN);
end;
case Message.Msg of
WM_MOUSEMOVE: Application.HintMouseMessage(Self, Message);
WM_LBUTTONDOWN, WM_LBUTTONDBLCLK:
begin
if FDragMode = dmAutomatic then //注意这里
begin
BeginAutoDrag; //注意这里,直接退出去，不会再产生click事件了，
//因此你可以继承BeginAutoDrag，在这里写onclick事件，或者直接在OnStartDrag里写onclick事件不就行了
Exit;
end;
Include(FControlState, csLButtonDown);
end;
WM_LBUTTONUP:
Exclude(FControlState, csLButtonDown);
else
with Mouse do
if WheelPresent and (RegWheelMessage <> 0) and
(Message.Msg = RegWheelMessage) then
begin
GetKeyboardState(KeyState);
with WheelMsg do
begin
Msg := Message.Msg;
ShiftState := KeyboardStateToShiftState(KeyState);
WheelDelta := Message.WParam;
Pos := TSmallPoint(Message.LParam);
end;
MouseWheelHandler(TMessage(WheelMsg));
Exit;
end;
end;
end
else if Message.Msg = CM_VISIBLECHANGED then
with Message do
SendDockNotification(Msg, WParam, LParam);
Dispatch(Message);
end;