单项选择题
YouarecreatingaWindowsFormsapplicationforafinancialserviceproviderbyusingthe.NETFramework3.5.Youhavetoimplementamultipledocumentinterface(MDI)intheapplicationtoallowuserstoopenmultiplefinancialdocumentssimultaneously.YouneedtoensurethatwheneverthechildMDIformiscreated,theapplicationdisplaysamessageinthetitlebaroftheparentMDIthatachildformhasreceivedfocus.Whatshouldyoudo?()
A.ImplementtheActivatedevent
B.ImplementtheMdiChildActivateevent
C.OverridetheOnParentVisibleChangedmethod
D.OverridetheOnParentBindingContextChangedmethod
A.NETFramework3.5.Youhavetoimplementamultipledocumentinterface(MDI)intheapplicationtoallowuserstoopenmultiplefinancialdocumentssimultaneously.YouneedtoensurethatwheneverthechildMDIformiscreated,theapplicationdisplaysamessageinthetitlebaroftheparentMDIthatachildformhasreceivedfocus.Whatshouldyoudo?()
A.ImplementtheActivatedevent
B.ImplementtheMdiChildActivateevent
C.OverridetheOnParentVisibleChangedmethod
D.OverridetheOnParentBindingContextChangedmethod