Misleading Error: "Parent class code is read only" (Visual Studio.NET)
I just had a strange error message from Visual Studio.NET when attempting to add a handler for
WM_DESTROY to a C++ dialog class. It said:
Add/Remove of the function is impossible because the parent class code is read only
Odd. There’s nothing read-only about any of this stuff.
It turns out that I’d previously had an
OnDestroy function in that class, and (somehow) the
ON_WM_DESTROY() macro had been left in the message map. This apparently confuses Visual Studio.
Just remove the old
ON_WM_DESTROY() line, and it’s happy to add a new one.