PRB: Spy Repeatedly Lists a Single Message

• Microsoft Windows Software Development Kit (SDK) versions 3.1, 3.0
• Microsoft Win32 Software Development Kit (SDK), versions 3.5, 3.51, 4.0

SYMPTOMS

SPY sometimes reports messages as having been sent twice. Messages from DDE conversations, especially the WM_DDE_DATA, WM_DDE_ACK, and WM_DDE_POKE messages, are the most often duplicated. This behavior can be seen by choosing All Windows from Spy's Windows menu, selecting DDE messages in Spy's Options dialog, and then running two applications that communicate using DDE.

CAUSE

Spy displays a message each time it is retrieved. If an application retrieves a message once by calling PeekMessage() with PM_NOREMOVE, and then again with GetMessage(), Spy will report it twice. Spy cannot determine that the message was already retrieved by the application. Since the application is using the message twice, the message should indeed be shown twice. This is a useful feature for determining how an application is handling the DDE messages sent to it.

Additional query words: 3.00 3.10 3.50 4.00 95 win16sdk

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Last Reviewed: March 4, 1999