Allow to hide AutoHideWindow by clicking the show button

[kice]

Changing the function here should do the trick

https://github.com/Dirkster99/AvalonDock/blob/e52d8cca62332b1997f4717aab35f505c2ea57d9/source/Components/AvalonDock/Controls/LayoutAnchorControl.cs#L132-L133

=>

if (_model.IsActive)
{
	_model.Root.Manager.HideAutoHideWindow(this);
	_model.IsActive = false;
}
else
{
	_model.Root.Manager.ShowAutoHideWindow(this);
	_model.IsActive = true;
}

In some cases, I cannot lose the focus all the time, for example: the panel is a WinForm control for some reasons, looks like window message was not forward to WPF window message loop, thus the focus still is the AutoHideWindow.

Also, VS have the this feature for a long time I believe and I think a lot of people use the same button to show/hide the thing.