Adding a Control per Mouse Click in Run Time - wpf

Question

public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
Button button1 = new Button();
Point tPosition = Mouse.GetPosition(this);
button1.Margin = new Thickness(tPosition.X,tPosition.Y,0,0) ;
button1.Width = 75;
this.AddChild(button1);
}
}
I think the code is pretty self-explanatory, I used a code that is approved in other thread here in stackoverflow, it doesn't give any error, but it also doesn't show up, do I need to refresh the window? And how?
by request, the XAML
<Window x:Class="Ampeldingensthingy.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid MouseLeftButtonDown="Grid_MouseLeftButtonDown" Name="hans">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="398*" />
<ColumnDefinition Width="105*" />
</Grid.ColumnDefinitions>
</Grid>
</Window>

Answer 1

Window can have only one children and I think you already have one that is Grid whose MouseButtonDown you subscribing. Give a name to that Grid and then replace
this.AddChild(button1);
with
grid.Children.Add(button1);
here grid is the name given to Grid.

Answer 2

The object "this" depicts the Window object here. Content of a ContentControl must be a single element. Hence append the Button that is "button1" inside a parent Grid. For example
private void Button_Click(object sender, RoutedEventArgs e)
{
Button button1 = new Button();
Point tPosition = Mouse.GetPosition(this);
button1.Margin = new Thickness(tPosition.X, tPosition.Y, 0, 0);
button1.Width = 75;
MainGrid.Children.Add(button1);
}
And in your Xaml
<Grid x:Name="MainGrid">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Button Click="Button_Click" Content="click" Grid.Row="1"/>
</Grid>

Answer 3

public partial class MainWindow : Window
{
public StackPanel SPanel{get;set;}
public MainWindow()
{
InitializeComponent();
SPanel = new StackPanel { Orientation = Orientation.Vertical };
}
private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
Button button1 = new Button();
Point tPosition = Mouse.GetPosition(this);
button1.Margin = new Thickness(tPosition.X,tPosition.Y,0,0) ;
button1.Width = 75;
SPanel.Children.Add(button1);
window.Content = SPanel;
}
}
try to do the same with a canvas. the buttons will popup at the position you gave them.