typedef void __fastcall (__closure *TBandMoveEvent)(System::TObject* Sender, Vcl::Controls::TControl* Control, System::Types::TRect &ARect);
Sender is the control bar in which a band is about to be moved.
Control is the control on the band that is about to be moved (usually a TToolBar object).
ARect is the area to which the control is about to be moved. This value can be adjusted from within the event handler.