procedure TControl.SetVisible(Value: Boolean);
begin
if FVisible <> Value then
begin
    VisibleChanging;
    FVisible := Value;
    Perform(CM_VISIBLECHANGED, Ord(Value), 0);
    RequestAlign;
end;
end;

procedure TWinControl.CMVisibleChanged(var Message: TMessage);
begin
if not FVisible and (Parent <> nil) then RemoveFocus(False);
if not (csDesigning in ComponentState) or
    (csNoDesignVisible in ControlStyle) then UpdateControlState;
end;

procedure TWinControl.UpdateShowing;
var
  ShowControl: Boolean;
  I: Integer;
begin
  ShowControl := (FVisible and (not (csDesigning in ComponentState) or not (csDesignerHide in ControlState)) or
    ((csDesigning in ComponentState) and not (csDesignerHide in ControlState)) and
not (csNoDesignVisible in ControlStyle)) and
not (csReadingState in ControlState) and not (csDestroying in ComponentState);
if ShowControl then
begin //这个时候如果是第一次显示，FHandle为0，就会调用CreateHandle来创建一个窗口句柄了，也就是说
    //在这个时候才真真实实的创建Windows的标准控件！
if FHandle = 0 then CreateHandle;
if FWinControls <> nil then
for I := 0 to FWinControls.Count - 1 do
        TWinControl(FWinControls[I]).UpdateShowing;//之后会更新属于这个控件容器的所有子控件显示
end;
if FHandle <> 0 then
if FShowing <> ShowControl then
begin
      FShowing := ShowControl;
try
        SetPerformingShowingChanged(Self);
try
          Perform(CM_SHOWINGCHANGED, 0, 0);
finally
          ClearPerformingShowingChanged(Self);
end;
except
        FShowing := not ShowControl;
raise;
end;
end;
end;

procedure TWinControl.CMRecreateWnd(var Message: TMessage);
var
  WasFocused: Boolean;
begin
  WasFocused := Focused;//先保存控件是否是焦点状态
  UpdateRecreatingFlag(True);//这个函数，我就不贴他的代码了，从他的代码中，我们可以看出来，这个函数
 //的目的是为所有的子控件打上重建的标记
try
    DestroyHandle;//释放句柄，同时释放所有子控件的句柄
    UpdateControlState;//更新控件状态，这个函数上面已经分析，会建立句柄，同时子控件句柄。
finally
    UpdateRecreatingFlag(False);//重建状态完成
end;
if WasFocused and (FHandle <> 0) then
    Windows.SetFocus(FHandle);//如果重建成功，并且原先有焦点，就恢复原先的焦点状态
end;