FIX: GPF/UAE When Assign NULL to VBM_GETPROPERTY of type HLSTD

The information in this article applies to:

- Microsoft Visual Basic programming system for Windows, version 2.0

SYMPTOMS

When you return a NULL in response to the VBM_GETPROPERTY message for a custom property of data type HLSTR, a General Protection (GP) fault or Unrecoverable Application Error (UAE) occurs.

Because of this problem, you cannot simply use the PF_fGetData flag with a custom property of data type HLSTR. What's more, you must use the PF_fGetMsg flag to ensure that the value of the property is never set to NULL. This information is taken from the CDK.TXT file provided with Microsoft Visual Basic Professional Edition version 2.0 for Windows.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Visual Basic Professional Edition version 2.0 for Windows. This problem was corrected in Microsoft Visual Basic version 3.0 for Windows.

MORE INFORMATION

Below is the information provided in the CDK.TXT file:

DT-HLSTR Properties and PF_fGetData

DT_HLSTR properties cannot use PF_fGetData by itself. They must also use PF_fGetMsg to avoid returning a NULL hlstr. See the MyTag property in the PIX example (PIX.C) for a guide for how to properly declare a HLSTR property and process the VBM_GETPROPERTY message.