https://community.graphisoft.com/t5/Archicad-C-API/How-To-Hook-And-Cancel-When-Delete-Element/m-p/338596#M1480 <P>Please Teach me.</P> <P>How To Hook And Cancel When Delete Element.</P> <P>I catch DELETE Handler&nbsp;</P> <P>&nbsp;</P> <LI-CODE lang="cpp">static GSErrCode __ACENV_CALL ElementEventHandler(const API_NotifyElementType *elemType) { GSErrCode err = NoError; switch (elemType-&gt;notifID) { case APINotifyElement_Delete: // I hope Cancel Delete Command By Guid break; default: err = APIERR_NOTSUPPORTED; break; };//sw return(err); } //------------------------------------- void SetHandler() { //Get Guid List ... //Set Handle for Delete Command ACAPI_Notify_InstallElementObserver(ElementEventHandler); for (auto&amp; guid: GuidList) { err = ACAPI_Element_AttachObserver(guid); } } </LI-CODE> <P>&nbsp;</P> Tue, 17 May 2022 15:50:00 GMT Kouichi 2022-05-17T15:50:00Z https://community.graphisoft.com/t5/Archicad-C-API/How-To-Hook-And-Cancel-When-Delete-Element/m-p/338596#M1480 <P>Please Teach me.</P> <P>How To Hook And Cancel When Delete Element.</P> <P>I catch DELETE Handler&nbsp;</P> <P>&nbsp;</P> <LI-CODE lang="cpp">static GSErrCode __ACENV_CALL ElementEventHandler(const API_NotifyElementType *elemType) { GSErrCode err = NoError; switch (elemType-&gt;notifID) { case APINotifyElement_Delete: // I hope Cancel Delete Command By Guid break; default: err = APIERR_NOTSUPPORTED; break; };//sw return(err); } //------------------------------------- void SetHandler() { //Get Guid List ... //Set Handle for Delete Command ACAPI_Notify_InstallElementObserver(ElementEventHandler); for (auto&amp; guid: GuidList) { err = ACAPI_Element_AttachObserver(guid); } } </LI-CODE> <P>&nbsp;</P> Tue, 17 May 2022 15:50:00 GMT https://community.graphisoft.com/t5/Archicad-C-API/How-To-Hook-And-Cancel-When-Delete-Element/m-p/338596#M1480 Kouichi 2022-05-17T15:50:00Z