IsMouseOver trigger doesn't work when using ShowDialog and borderless window

Question

I have two Windows for an application. One of them is MainWindow and the other is for settings. SettingsWindow opens when settings but

Answer 1

I think you have to observe the mouse position manually. For this you could use the code behind posted by Peheje here.

I used this to program a working example. While leaving your window, the Button gets the correct style.

using System.Runtime.InteropServices;
using Point = System.Drawing.Point;

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetCursorPos(ref Point lpPoint);

public bool IsMouseOverButton {
    get { return _isMouseOverButton; }
    set {
        if (value == _isMouseOverButton) return;
        _isMouseOverButton = value;
        OnPropertyChanged();
    }
}

public SettingsWindow()
{
    InitializeComponent();

    new Thread(() =>
    {
        while (true)
        {
            //Logic
            Point p = new Point();
            GetCursorPos(ref p);

            //Update UI
            Application.Current.Dispatcher.Invoke(() =>
            {
                double btnLeft = DlgWindow.Left;
                double btnRight = btnLeft + DlgBtn.ActualWidth;
                double btnBottom = DlgWindow.Top + DlgWindow.ActualHeight;
                double btnTop = btnBottom - DlgBtn.ActualHeight;

                IsMouseOverButton =
                    p.X >= btnLeft && p.X <= btnRight &&
                    p.Y >= btnTop && p.Y <= btnBottom;
            });

            //async wait (non blocking)
            (new ManualResetEvent(false)).WaitOne(100);
        }
    }).Start();
}

xaml