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POCan't catch sleep/suspend messages (winXP)
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copied!<p>My app needs to block sleep/hibernate mode. I have the code in place, but after successfully catching the <strong>WM_POWERBROADCAST</strong> message, neither <strong>PBT_APMQUERYSUSPEND</strong> nor <strong>PBT_APMQUERYSTANDBY</strong> are being caught successfully. Interestingly, the <strong>PBT_APMRESUMECRITICAL</strong> and <strong>PBT_APMRESUMEAUTOMATIC</strong> messages <em>are</em> being caught by my app.</p> <p>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?</p> <p>This <a href="https://stackoverflow.com/questions/629240/prevent-windows-from-going-into-sleep-when-my-program-is-running">Q&A</a> [stackoverflow.com] helped, btw, but again, the messages don't seem to be making it to my app.</p> <p>My code (w/ event logging code removed for brevity):</p> <pre><code> 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); } </code></pre>

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