delphi DateTimePicker 宽度如何与Delphi自带Style同步

解决办法1：把自带 style 的 client 项关闭

解决办法2：

网上一搜，Stack Overflow 给出了方案——去掉自动绘制 style，去提取 style 的相关元素来设置 CalColors 属性。

尝试一下，效果基本能接受了。记在这里备查。

http://stackoverflow.com/questions/10335310/style-properties-for-tdatetimepicker

uses

  Winapi.CommCtrl,

  Vcl.Styles,

  Vcl.Themes,

  uxTheme;

Procedure SetVclStylesColorsCalendar( DateTimePicker: TDateTimePicker);

Var

  LTextColor, LBackColor : TColor;

begin

   uxTheme.SetWindowTheme(DateTimePicker.Handle, '', '');//disable themes in the calendar

   //get the vcl styles colors

   LTextColor:=StyleServices.GetSystemColor(clWindowText);

   LBackColor:=StyleServices.GetSystemColor(clWindow);

   DateTimePicker.Color:=LBackColor;

   //set the colors of the calendar

   DateTimePicker.CalColors.BackColor:=LBackColor;

   DateTimePicker.CalColors.MonthBackColor:=LBackColor;

   DateTimePicker.CalColors.TextColor:=LTextColor;

   DateTimePicker.CalColors.TitleBackColor:=LBackColor;

   DateTimePicker.CalColors.TitleTextColor:=LTextColor;

   DateTimePicker.CalColors.TrailingTextColor:=LTextColor;

end;

procedure TForm2.DateTimePicker1DropDown(Sender: TObject);

var

  hwnd: WinAPi.Windows.HWND;

begin

  hwnd := SendMessage(TDateTimePicker(Sender).Handle, DTM_GETMONTHCAL, 0,0);

  uxTheme.SetWindowTheme(hwnd, '', '');//disable themes in the drop down window

end;

procedure TForm2.FormCreate(Sender: TObject);

begin

  SetVclStylesColorsCalendar(DateTimePicker1);

end;

来源：https://www.cnblogs.com/codingnote/archive/2014/10/24/4047264.html