运行时实现组件移动，改变大小

在窗体上放置Panel1组件，
//进入移动状态
procedure TMainForm.Panel1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if (Button=mbLeft) then
begin
SendMessage(panel1.Handle,WM_LBUTTONUP,0,0);
SendMessage(panel1.Handle,WM_NCLBUTTONDOWN,HTCaption,0);
end;
end;
//进入改变大小状态
procedure TMainForm.Panel1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if (Button=mbLeft) then
begin
SendMessage(panel1.Handle,WM_LBUTTONUP,0,0);
SendMessage(panel1.Handle,WM_NCLBUTTONDOWN,HTCaption,0);
end;
end;