Sizing down the ClientSize on Mac make the windows go down

[NicolasDorier]

This hack solves it.

void ResizeHack()
{
    Size newSize = MainViewModel.IsVisible ? ExpandedSize : NormalSize;

    if (newSize != this.ClientSize)
    {
        this.ClientSize = newSize;
        // On Mac, resizing down will make the windows jump down, so we need to set it back up
        if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) && newSize == NormalSize)
        {
            this.Position = this.Position.WithY(this.Position.Y - (int)(ExpandedSize.Height - NormalSize.Height));
        }
    }
}