[in] A handle to the parent window of the progress indicator that is displayed while the form is downloaded. The ulUIParam parameter is ignored unless the MAPI_DIALOG flag is set in the ulFlags parameter.
[in] A bitmask of flags that controls how the form is downloaded. The following flag can be set:
Displays a user interface to provide status or prompt the user for more information. If this flag is not set, no user interface is displayed.
[in] A pointer to a form information object for the form to be downloaded.
Form viewers call the IMAPIFormMgr::PrepareForm method to download a form from a form container for opening. Most form viewers do not need to call PrepareForm, because both the IMAPIFormMgr::CreateForm and IMAPIFormMgr::LoadForm methods call PrepareForm, if necessary.
You can use PrepareForm to obtain the dynamic-link libraries (DLLs) and other files associated with a form to modify them. If the modified form is loaded back into its form container, it must be reinstalled.