Yes, WPF. The learning curve is steep, but what amazing things you can do with it!
Look at this hexagon window for instance. Serves no purpose in a business environment I guess, but in a gaming situation it could work. For me, it was just fun to get this up and running.
I’m using VS 2017. Start up a new WPF window project. Call it HexagonWindow and fill in the missing code.
I still don’t understand all the intricacies of WPF, I’m just a mere mortal human being, but my quest on the subject is ongoing. Why don’t some of you get there feet wet and give it a try! Tutorials can be found on a site starting with the letter G.

Window x:Class="HexagonWindow.MainWindow"
            Title="Hexa" Height="300" Width="300" WindowStyle="None"
            AllowsTransparency="True" Background="Transparent" MouseLeftButtonDown="Window_MouseLeftButtonDown">
            <!--Points="100,0 200,0 300,100 300,200 200,300 100,300 0,200 0,100" use these points for octagon window-->
            <Polygon  Points="75,0 225,0 300,150 225,300 75,300 0,150"  Stroke="Red" StrokeThickness="3" Fill="LightBlue"></Polygon>
            <Button Content = "X" Height="20" Width="20" Margin="150,0,0,0" Click="Button_Click" VerticalAlignment="Top"></Button>
            <StackPanel Height="80" Width="240">
                <TextBlock HorizontalAlignment="Center" Margin="5" Height="20" Text="He! I'm a hexagonal window!"></TextBlock>
                <TextBlock HorizontalAlignment="Center" Text="Drag me, by clicking the left mouse button"></TextBlock>

    using System.Windows;
    using System.Windows.Input;
    namespace HexagonWindow
        /// <summary>
        /// Interaction logic for MainWindow.xaml
        /// MainWindow is the hexagon window here
        /// </summary>
        public partial class MainWindow : Window
            public MainWindow()
            private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
            private void Button_Click(object sender, RoutedEventArgs e)

Oops, this should have been a code snippet. Apparently I forgot to mark it as such. :(