How to get FrameworkElement properties before its unloading

It is need to realize UI settings system - loading/saving some properites of UI elements (which can be modified by user in runtime) from/into persistent storage. For example:

• DevExpress grid control - columns width's, visibility, summary area and so on (this control has set of methods pairs like RestoreLayoutFrom/SaveLayoutTo, but SaveLayoutToStream(Xml) doesnt work in grid.Unloaded handler - when grid is disconnected from PresentationSource)
• grid rows/columns, which widths/heights can be adjusted by user via GridSplitter
• sizeable popup controls

It is easy to set up controls properties from settings storage after controls loading/initializing/etc, but how catch the moment before controls unloading (when they still remains in visual tree) in order to retrieve their settings for saving?

Short description

I intend to create singleton - UISettingsManager, which inside has a Dictionary with pairs of [element Uid, element settings data]. In visual container (Window, UserControl) this manager can be used in a way like this:

public partial class PageHeader : UserControl
{
    public PageHeader()
    {
        InitializeComponent();

        UISettingsManager.RestoreSettings(myGridControl);
        UISettingsManager.RestoreSettings(myPopup);
    }
}

myGridControl & myPopup has unique Uid's (in application scope), so UISettingsManager can retrieve their settings from inner dictionary & apply it to the controls; of course UISettingsManager knows, how to work with some different types of controls.

But when it is the right moment to store settings开发者_如何学编程 of controls, which container is Window or UserControl?

I would use the Window's Closing event.

public class MyWindow : Window
{
    public MyWindow()
    {
        this.Closing += new System.ComponentModel.CancelEventHandler(MyWindow_Closing);
    }

    void MyWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
    {
        // Save what I want to here
    }
}

This would be the safest bet, because you will always, at some point, close the window.

However, there may be alternatives, including the Unloaded event for a user control.