PRB: Helpstring Information May Be Lost During COM Interop

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This article was previously published under Q317116

SYMPTOMS

If the helpstring attribute is used in the type library for methods and properties of COM interfaces, and if you use this COM object from a .NET application, the help text that the helpstring specifies is not available.

Similarly, when you generate a type library for the .NET class, the type library may not contain the documentation for the classes and methods.

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CAUSE

The problem occurs because Tlbimp.exe and Tlbexp.exe do not currently generate the helpstring information.

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STATUS

This behavior is by design.

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MORE INFORMATION

Steps to Reproduce the Behavior

In Visual Basic .NET, create a new Windows Application project.
Right-click Toolbox, and then click Customize Toolbox.
Click the COM components tab, add Microsoft FlexGrid Control to the tab, and then add the FlexGrid control to the form.
In the properties pane, select FixedRows. Note that no description for this property appears at the bottom of the properties pane.
Open the type library of Msflxgrd.ocx (the Microsoft FlexGrid Control) in the OLE/COM Object Viewer, and note that the FixedRows property has a helpstring attribute with a value of Returns/sets the total number of fixed (non-scrollable) columns or rows for a FlexGrid.