PowerWriteACValueIndex changes are applied but not used - windows

Question

We use the methods PowerWriteACValueIndex and PowerWriteDCValueIndex to set the behavior of the sleep and shutdown button to Do nothing. When these methods are used to change the value this is reflected in the Control Panel, both button behaviors are changed to Do nothing. However the sleep and power button still function as before. After manually changing the behavior in the control panel to a different value and back the changes are applied. Am I using these methods incorrectly?
public static void DisableButtons()
{
Guid schemeId = GetActivePowerScheme();
DisablePowerAndSleepButtons(schemeId);
}
private static void DisablePowerAndSleepButtons(Guid schemeId)
{
// Lid close action
PowerWriteValueIndex(schemeId, ref PowrProf.SUBGROUP_BUTTONS,
ref PowrProf.OPTION_LIDACTION, PowrProf.ACTION_DO_NOTHING);
// Power button action
PowerWriteValueIndex(schemeId, ref PowrProf.SUBGROUP_BUTTONS,
ref PowrProf.OPTION_PBUTTONACTION, PowrProf.ACTION_DO_NOTHING);
// Sleep button action
PowerWriteValueIndex(schemeId, ref PowrProf.SUBGROUP_BUTTONS,
ref PowrProf.OPTION_SBUTTONACTION, PowrProf.ACTION_DO_NOTHING);
}
// Helper method that changes both the AC power setting and the DC (battery) power
// setting.
private static void PowerWriteValueIndex(Guid schemeGuid,
ref Guid subGroupOfPowerSettingsGuid, ref Guid powerSettingGuid, uint valueIndex)
{
// When on AC power
var hr = NativeMethods.PowerWriteACValueIndex(IntPtr.Zero, ref schemeGuid,
ref subGroupOfPowerSettingsGuid, ref powerSettingGuid, valueIndex);
if (hr != 0)
{
Console.WriteLine("Failed to write AC value");
}
// When on DC power (battery)
hr = NativeMethods.PowerWriteDCValueIndex(IntPtr.Zero, ref schemeGuid,
ref subGroupOfPowerSettingsGuid, ref powerSettingGuid, valueIndex);
if (hr != 0)
{
Console.WriteLine("Failed to write DC value");
}
}
private static Guid GetActivePowerScheme()
{
IntPtr ptrActiveGuid = IntPtr.Zero;
try
{
var hr = NativeMethods.PowerGetActiveScheme(IntPtr.Zero, ref ptrActiveGuid);
if (hr == 0)
{
var activeScheme = (Guid)Marshal.PtrToStructure(ptrActiveGuid, typeof(Guid));
return activeScheme;
}
return Guid.Empty;
}
finally
{
Marshal.FreeHGlobal(ptrActiveGuid);
}
}
private static class NativeMethods
{
[DllImport("powrprof.dll")]
public static extern uint PowerGetActiveScheme(IntPtr UserRootPowerKey, ref IntPtr ActivePolicyGuid);
[DllImport("powrprof.dll")]
public static extern uint PowerWriteACValueIndex(IntPtr RootPowerKey, ref Guid SchemeGuid, ref Guid SubGroupOfPowerSettingsGuid, ref Guid PowerSettingGuid, uint AcValueIndex);
[DllImport("powrprof.dll")]
public static extern uint PowerWriteDCValueIndex(IntPtr RootPowerKey, ref Guid SchemeGuid, ref Guid SubGroupOfPowerSettingsGuid, ref Guid PowerSettingGuid, uint DcValueIndex);
}
/// <summary>
/// Collections of guids to identify settings in PowrProf.dll
/// Source: http://adirondackpc.com/publicfiles/nos3s4-full.txt
/// </summary>
private static class PowrProf
{
public static Guid SUBGROUP_NONE = new Guid("fea3413e-7e05-4911-9a71-700331f1c294");
public static Guid SUBGROUP_SLEEP = new Guid("238c9fa8-0aad-41ed-83f4-97be242c8f20");
public static Guid SUBGROUP_VIDEO = new Guid("7516b95f-f776-4464-8c53-06167f40cc99");
public static Guid SUBGROUP_BUTTONS = new Guid("4f971e89-eebd-4455-a8de-9e59040e7347");
// Top level options
public static Guid OPTION_CONSOLELOCK = new Guid("0e796bdb-100d-47d6-a2d5-f7d2daa51f51");
// Sleep options
public static Guid OPTION_RTCWAKE = new Guid("bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d");
// Turn the computer to sleep after x seconds, minmum value: 0, maximum value: 4294967295
public static Guid OPTION_STANDBYIDLE = new Guid("29f6c1db-86da-48c5-9fdb-f2b67b1f44da");
// Hybernate the computer after x seconds, minmum value: 0, maximum value: 4294967295
public static Guid OPTION_HYBERNATEIDLE = new Guid("9d7815a6-7ee4-497e-8888-515a05f02364");
// Display options
// Display brightness, minimum value: 0, maximum value: 100
public static Guid OPTION_BRIGHTNESS = new Guid("aded5e82-b909-4619-9949-f5d71dac0bcb");
// Dim display after x seconds, minmum value: 0, maximum value: 4294967295
public static Guid OPTION_VIDEODIM = new Guid("3c0bc021-c8a8-4e07-a973-6b14cbcb2b7e");
// Turn off display after x seconds, minmum value: 0, maximum value: 4294967295
public static Guid OPTION_VIDEOIDLE = new Guid("3c0bc021-c8a8-4e07-a973-6b14cbcb2b7e");
// Button options
// Lid close action
public static Guid OPTION_LIDACTION = new Guid("5ca83367-6e45-459f-a27b-476b1d01c936");
// Power button action
public static Guid OPTION_PBUTTONACTION = new Guid("7648efa3-dd9c-4e3e-b566-50f929386280");
// Sleep button action
public static Guid OPTION_SBUTTONACTION = new Guid("96996bc0-ad50-47ec-923b-6f41874dd9eb");
// Button actions
public static uint ACTION_DO_NOTHING = 0;
public static uint ACTION_SLEEP = 1;
public static uint ACTION_HIBERNATE = 2;
public static uint ACTION_SHUT_DOWN = 3;
// Universal constants
public static uint FALSE = 0;
public static uint TRUE = 1;
public static uint NEVER = 0;
}

Answer 1

You need to call PowerSetActiveScheme after calling either PowerWriteDCValueIndex or PowerWriteACValueIndex.
It's on the documentation under the remarks section:
Changes to the settings for the active power scheme do not take effect until you call the PowerSetActiveScheme function.