InstallAware

Where can I find the documentation to create plugins?

E.g. in the comment it says see help but the InstallAware help did not contain any specific help:

/* Design Time Function
=====================
This function is called during Design Time
Window: Handle to parent window
State: State of plug-in controls, as provided to the IDE previously
NewState: New state of plug-in controls, as edited by user
See help for details
*/

__declspec(dllexport) int WINAPI DesignTimeEdit(int Window, const char* State, const char* NewState)

Thanks.

Its in the help file, under the Plug-In Development book.