FEditorDelegates::OnMapOpened : GWorld will be the new loaded world.
PIE
FEditorDelegates::StartPIE: Sent when a PIE session has been requested to Start
FEditorDelegates::PreBeginPIE: Sent when a PIE session is beginning (before we decide if PIE can run - allows clients to avoid blocking PIE)
FEditorDelegates::BeginPIE: Sent when a PIE session is beginning (but hasn’t actually started yet)
FEditorDelegates::PostPIEStarted: Sent when a PIE session has fully started and after BeginPlay() has been called
FEditorDelegates::PrePIEEnded: Sent when a PIE session is ending, before anything else happens
FEditorDelegates::EndPIE: Sent when a PIE session is ending
FEditorDelegates::ShutdownPIE: Sent when a PIE session has completely shutdown
FEditorDelegates::PausePIE: Sent when a PIE session is paused
FEditorDelegates::ResumePIE: Sent when a PIE session is resumed
FEditorDelegates::SingleStepPIE: Sent when a PIE session is single-stepped
FEditorDelegates::OnPreSwitchBeginPIEAndSIE: Sent just before the user switches between from PIE to SIE, or vice-versa. Passes in whether we are currently in SIE
FEditorDelegates::OnSwitchBeginPIEAndSIE: Sent after the user switches between from PIE to SIE, or vice-versa. Passes in whether we are currently in SIE
FEditorDelegates::CancelPIE: Sent when a PIE session is cancelled