My app needs to block sleep/hibernate mode. I have the code in place, but after successfully catching the WM_POWERBROADCAST message, neither PBT_APMQUERYSUSPEND nor PBT_APMQUERYSTANDBY are being caught successfully. Interestingly, the PBT_APMRESUMECRITICAL and PBT_APMRESUMEAUTOMATIC messages are being caught by my app.
Bottom line question: is there any reason why my app would fail to catch the standby/suspend messages, but succeed in catching the resume messages?
This Q&A [stackoverflow.com] helped, btw, but again, the messages don't seem to be making it to my app.
My code (w/ event logging code removed for brevity):
protected override void WndProc(ref System.Windows.Forms.Message m)
{
// Power status event triggered
if (m.Msg == (int)NativeMethods.WindowMessage.WM_POWERBROADCAST)
{
// Machine is trying to enter suspended state
if (m.WParam.ToInt32() == (int)NativeMethods.WindowMessage.PBT_APMQUERYSUSPEND ||
m.WParam.ToInt32() == (int)NativeMethods.WindowMessage.PBT_APMQUERYSTANDBY)
{
// Have perms to deny this message?
if((m.LParam.ToInt32() & 0x1) != 0)
{
// If so, deny broadcast message
m.Result = new IntPtr((int)NativeMethods.WindowMessage.BROADCAST_QUERY_DENY);
}
}
return; // ?!
}
base.WndProc(ref m);
}
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