How to cancel the window changing

[Ellis]

Hi,
   i have a problem canceling the ActiveWindowChanging events.
When i enter in this event i check if the last ActiveWindow is updated. If not i ask user to chose to save, or not, data to db.
If user chose to save, i update data in db, and proced changing the Active Window, as user wants. But when i save data, if i get an exception, i send a msgbox to user, and i want to "reactivate" the last ActiveWindow. In this way, the user can edit data to complete it or discard it.
How can i cancel the window changing?
I try with e.cancel = true, but the program loops :(

    Private Sub RadDock1_ActiveWindowChanging(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.Docking.DockWindowCancelEventArgs) Handles RadDock1.ActiveWindowChanging
        ' Salvo il Layout del tab che sto chiudendo
        For Each c As Control In RadDock1.ActiveWindow.Controls
            Select Case c.GetType.ToString
                Case "Commesse"
                    Dim mycontrol As AnagraficaCommesse = TryCast(c, AnagraficaCommesse)
                    mycontrol.SaveGridLayout()
                Case "Articoli"
                    Dim mycontrol As Commesse_Articoli = TryCast(c, Commesse_Articoli)
                    mycontrol.SaveGridLayout()
                    If mycontrol.RadGridView1.IsInEditMode() Then
                        If MsgBox("Un record non è stato salvato! Si desidera salvarlo ora?", MsgBoxStyle.YesNo, "Salvare i dati?") = MsgBoxResult.Yes Then
                            Try
                                mycontrol.RadGridView1.EndEdit()
                                mycontrol.UpdateDataSource()
                            Catch ex As Exception
                                MsgBox("Si è verificato un problema durante il salvataggio dei dati. Controllare che i dati inseriti siano corretti", MsgBoxStyle.Critical, "Errore")
                                e.Cancel = True
                            End Try
                        Else
                            mycontrol.RadGridView1.EndEdit()
                        End If
                    End If
            End Select
        Next
    End Sub

I'm sorry if code is not clear; this is only for understand if i wrong something in it, with the e.cancel = true.

Thanks

[Martin Vasilev]

Hi Ellis,

Thank you for writing.

Actually, canceling the ActiveWindowChanging event works as expected and it prevents changing the RadDock.ActiveWindow reference. The only meaningful canceling of this event is if there is a programmatically active window swapping, through a code. If active window is changed through focus change (the end user clicks on a control in a different window) then canceling that event does not make sense, because it cannot prevent focus change. For validation scenarios it will be better to use ToolWindow.Validating event instead ActiveWindowChanging.

Regards,
Martin Vasilev
the Telerik team