Debugging Timer Functions Requires Hard-Mode Debugging

ID: Q131897

The information in this article applies to:

The Integrated Debugger, included with:
- Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52

SUMMARY

When setting a breakpoint in a Windows timer function (TimerProc), you might receive this error message:

Cannot process breakpoint while debugger already stopped

To resolve this, you need to place the debugger into hard mode. On the Options menu, click Debug, and then choose Hard as the debugging mode.

MORE INFORMATION

By placing the debugger into hard mode, you ensure that the application cannot start or switch to any other applications. This makes the application "task exclusive," and all keyboard and mouse messages are sent only to the debugger and its target application.

There are times when the debugger may destabilize Windows by interacting with it. This can happen when the debugger stops while the system is in a critical (non-interruptable) processing stage (stopping at a breakpoint, stepping through code, encountering an exception, and so on). This can occur while debugging things like menu events, system modal windows, or intertask messages.

Hard-mode debugging is especially useful when debugging time-critical events such as timer events and intertask DDE transactions.

NOTE: Hard-mode debugging is not available when you are using the 16-bit debugging environment under Windows NT.

Additional query words: kbinf 1.00 1.50


Keywords          : kb16bitonly 
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Last Reviewed: July 23, 1999