interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
ComboBox1: TComboBox;
Memo1: TMemo;
procedure ComboBox1Change(Sender: TObject);
procedure FormShow(Sender: TObject);
public
procedure FillComboBox(combobox: TComboBox);
procedure FillMemo(timezone: string; memo: TMemo);
end;

var
Form1: TForm1;

implementation

uses
Registry;
{$R *.dfm}

{ TForm1 }

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
if Sender is TComboBox then
FillMemo(TComboBox(Sender).Text,Memo1);
end;

procedure TForm1.FillComboBox(combobox: TComboBox);
var
reg: TRegistry;
begin
reg:= TRegistry.Create(KEY_READ);
combobox.Items.BeginUpdate;
try
comboBox.Items.Clear;
reg.RootKey:= HKEY_LOCAL_MACHINE;
if reg.OpenKey('SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones',False) then
reg.GetKeyNames(combobox.Items);
finally
reg.Free;
combobox.Items.EndUpdate;
end;
end;

procedure TForm1.FillMemo(timezone: string; memo: TMemo);
var
reg: TRegistry;
regkey: string;
tzi: TTimeZoneInformation;
begin
memo.Lines.Clear;
reg:= TRegistry.Create(KEY_READ);
regkey:= Format('SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\%s',[timezone]);
try
reg.RootKey:= HKEY_LOCAL_MACHINE;
if reg.OpenKey(regkey,False) then
begin
memo.Lines.Add(Format('Daylight Time Display: %s',[reg.ReadString('Dlt')]));
memo.Lines.Add(Format('Standard Time Display: %s',[reg.ReadString('Std')]));
reg.ReadBinaryData('TZI',tzi,sizeof(tzi));
memo.Lines.Add(Format('Bias: %d minutes',[tzi.Bias]));
end;
finally
reg.Free;
end;
end;

procedure TForm1.FormShow(Sender: TObject);
begin
FillComboBox(ComboBox1);
end;

end.