Ensure WPF Taskbar Window Preview is actualized

Question

How can I ensure that the hower preview of my WPF application (.net 4) is refreshed when the user places the mouse over the taskbar icon.
I have an app that visualizes some status values. If the app window is minimized and the user hovers over the taskbar button, the preview window that is shown shows the last view of the window at which the window was active. However I would like to have an actualized view.
Is there a possiblity to achieve that?

Answer 1

I believe you'd need to customize the preview, as described here (under the Customizing Preview section). Which leverages the Windows API Code Pack for Microsoft® .NET Framework.

An example can be found here, but looks like:

TabbedThumbnail preview = new TabbedThumbnail(parentForm.Handle, childForm.Handle);
TaskbarManager.Instance.TabbedThumbnail.AddThumbnailPreview(preview);
preview.TabbedThumbnailBitmapRequested += (o, e) =>
    {
        Bitmap bmp = new Bitmap(width, height);

        // draw custom bitmap...

        e.SetImage(bmp);
        e.Handled = true;
    };

Another example, can be found here which states:

The CustomWindowsManager class provides an abstraction of a customized window thumbnail preview and live preview (peek), including the facilities to receive a notification when a preview bitmap is requested by the Desktop Window Manager (DWM) and to automatically grab the preview bitmap of a window.

The download link for this code is here, which includes the CustomWindowsManager class. This appears to provide the live preview.

Answer 2

You probably can't. Windows 7 pipes the graphics of an open window to the live preview from the Taskbar. It can't know what the window now looks like while it is minimized because it isn't being drawn at all.

I guess it's not impossible to do custom thumbnails. Aside from CodeNaked's answer, I also found this article, which even includes multiple thumbnails from the same app.