[This is preliminary documentation and subject to change.]
Recommendation (Designed for Microsoft® Windows® Logo)
Your application should not request any user input while it is processing a WM_POWERBROADCAST sleep or query message.
Your application can display a confirmation dialog box only if both of the following conditions are met:
Pretesting OnNow/ACPI Support.
http://www.microsoft.com/hwdev/onnow.htm for information about the OnNow initiative and technical specifications.