I have to stop windows from going into sleep when my program is running.
And I don't only want to prevent the sleep-timer, I also want to cancel the sleep-event if I press the sleep-button or in any other way actively tell the computer to sleep. Therefore SetThreadExecutionState is not enough.
Or…I don't actually have to prevent the sleep completely, only delay it 5-10sec to allow my program to finish a task.
(I know that this is bad program behavior but it's only for personal use.)
Best Answer
After considering vim's answer
with the linked AvailabilityRequests.docx on msdn which is exhausting to get into it (too much to read), I have searched the web for a concrete example in c# that is based on the PowerCreateRequest and found http://go4answers.webhost4life.com/Example/problem-monitor-wakeup-service-windows7-12092.aspx [EDIT 2016 - isn't available anymore]
Copied and adapted it to my needs (PInvoke of CloseHandle copied from msdn):