Question

I have a WPF window with expandable panel (via Expander). The panel is on the left side of the window, and when expanded the window grows to fit the content.

By default, windows are anchored to the top-left, so my window grows to the right. I’d like the window to grow to the left.

I tried to do the following in the Window.SizeChanged event:

private void onWindowSizeChanged(object sender, SizeChangedEventArgs e)
{
    Left -= (e.NewSize.Width - e.PreviousSize.Width)
}

and it works, but the growth is jerky, and I’d like to find a smoother solution.

Answer 1

I managed to overcome this using a simple solution: Hide & Show.

Here’s the code:

protected override void OnRenderSizeChanged(SizeChangeInfo sizeInfo)
{
    if (!sizeInfo.WidthChanged)
    {
        base.OnRenderSizeChanged(sizeInfo);
        return;
    }
    Hide();
    base.OnRenderSizeChanged(sizeInfo);
    Left -= (sizeInfo.NewSize.Width - sizeInfo.PreviousSize.Width);
    Show();
}

I replaced the event handler for Window.SizeChanged with this override of FrameworkElement.OnRenderSizeChanged.