How to handle the moment when an active tab is changed in Tabbed MDI mode

To accomplish this task, you can handle the DocumentManager.View.DocumentActivated event. Use the approach described in the following article to access the DocumentManager component: How to: Access the Document Manager.

You can also reuse the functionality provided by our WinWindowTemplateController:

C#
public class MyWinWindowTemplateController : WinWindowTemplateController {  
    protected override void OnDocumentActivated(DevExpress.XtraBars.Docking2010.Views.DocumentEventArgs e) {  
        base.OnDocumentActivated(e);  
        if (e.Document.Form is IViewHolder) {  
            View activeView = ((IViewHolder)e.Document.Form).View;  
        }  
    }  
}  

Here is an example of how to handle the DocumentActivated event in older XAF versions:

C#
using DevExpress.ExpressApp.Templates;  
using DevExpress.ExpressApp.Win.Templates;  

public class MainWindowController : WindowController {  
    public MainWindowController() {  
        TargetWindowType = WindowType.Main;  
    }  
    protected override void OnActivated() {  
        base.OnActivated();  
        Frame.TemplateChanged += Frame_TemplateChanged;  
    }  
    void Frame_TemplateChanged(object sender, EventArgs e) {  
        if (((IModelOptionsWin)Application.Model.Options).UIType == UIType.TabbedMDI && Frame.Template is IXafDocumentsHostWindow) {  
            ((IXafDocumentsHostWindow)Frame.Template).DocumentManager.ViewChanged += DocumentManager_ViewChanged;  
            ((IXafDocumentsHostWindow)Frame.Template).DocumentManager.ViewChanging += DocumentManager_ViewChanging;  
        }  
    }  
    void DocumentManager_ViewChanging(object sender, DevExpress.XtraBars.Docking2010.ViewEventArgs args) {  
        args.View.DocumentActivated -= View_DocumentActivated;  
    }  
    void DocumentManager_ViewChanged(object sender, DevExpress.XtraBars.Docking2010.ViewEventArgs args) {  
        args.View.DocumentActivated += View_DocumentActivated;  
    }  
    void View_DocumentActivated(object sender, DevExpress.XtraBars.Docking2010.Views.DocumentEventArgs e) {  
        if (e.Document.Form is IViewHolder) {  
            View activeView = ((IViewHolder)e.Document.Form).View;  
        }  
    }  
    protected override void OnDeactivated() {  
        base.OnDeactivated();  
        Frame.TemplateChanged -= Frame_TemplateChanged;  
        if (Frame.Template is IXafDocumentsHostWindow) {  
            ((IXafDocumentsHostWindow)Frame.Template).DocumentManager.ViewChanged -= DocumentManager_ViewChanged;  
            ((IXafDocumentsHostWindow)Frame.Template).DocumentManager.ViewChanging -= DocumentManager_ViewChanging;  
        }  
    }  
}  

Here is an example for older XAF versions that use the previous version of our frame templates:

C#
public class MainWindowController : WindowController {  
    public MainWindowController() {  
        TargetWindowType = WindowType.Main;  
    }  
    protected override void OnActivated() {  
        base.OnActivated();  
        Frame.TemplateChanged += new EventHandler(Frame_TemplateChanged);  
    }  
    void Frame_TemplateChanged(object sender, EventArgs e) {  
        if (((IModelOptionsWin)Application.Model.Options).UIType == UIType.TabbedMDI && Frame.Template is MainFormTemplateBase) {  
            ((MainFormTemplateBase)Frame.Template).DocumentManager.View.DocumentActivated += new DevExpress.XtraBars.Docking2010.Views.DocumentEventHandler(View_DocumentActivated);  
        }  
    }  
    void View_DocumentActivated(object sender, DevExpress.XtraBars.Docking2010.Views.DocumentEventArgs e) {  
        if (e.Document.Form is XtraFormTemplateBase) {  
            View activeView = ((XtraFormTemplateBase)e.Document.Form).View;  
            XtraMessageBox.Show(activeView.Id);  
        }  
    }  
    protected override void OnDeactivated() {  
        base.OnDeactivated();  
        Frame.TemplateChanged -= new EventHandler(Frame_TemplateChanged);  
    }  
}