Question

I succeed to change the TimeZone and daylight time in Windows using SetTimeZoneInformation but even when setting wMonth to 0, the checkbox in datetime.cpl is checked.

TIME_ZONE_INFORMATION actual = new TIME_ZONE_INFORMATION();
NativeMethods.GetTimeZoneInformation(out actual);
// Datetime.cpl put the standard time in daylight time and add the regkey
// When executing this -> Regkey is not set automatically
actual.DaylightBias = actual.StandardBias;
actual.DaylightDate = actual.StandardDate;
actual.DaylightName = actual.StandardName;
RunWin32Method(() => NativeMethods.SetTimeZoneInformation(ref newZone));
NativeMethods.SendMessageTimeout(NativeMethods.HWND_BROADCAST, NativeMethods.WM_SETTING_CHANGE, IntPtr.Zero, IntPtr.Zero, 0x00, 1000, out ptr)

// MSDN said
// When executing this -> Regkey is not set automatically
actual.StandardDate.Month = 0;
RunWin32Method(() => NativeMethods.SetTimeZoneInformation(ref newZone));
NativeMethods.SendMessageTimeout(NativeMethods.HWND_BROADCAST, NativeMethods.WM_SETTING_CHANGE, IntPtr.Zero, IntPtr.Zero, 0x00, 1000, out ptr)

How can I change this?
Need I create/delete the DisableAutoDaylightTimeSet registry key manually too?

Thanks

Answer 1

Create / Delete the registry key manually is the way to do…