Node editor - Added node creation by dropping cables in empty space

Node editor - Added undo/redo to static value nodes
UI - Throw exception when binding a non-reactive view to an activatable view model

src/Avalonia/Artemis.UI.Shared/Behaviors/LostFocusTextBoxBindingBehavior.cs

@@ -0,0 +1,56 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Data;
+using Avalonia.Interactivity;
+using Avalonia.Xaml.Interactivity;
+
+namespace Artemis.UI.Shared.Behaviors;
+
+/// <summary>
+///     Represents a behavior that can be used to make a text box only update it's binding on focus loss.
+/// </summary>
+public class LostFocusTextBoxBindingBehavior : Behavior<TextBox>
+{
+    public static readonly StyledProperty<string> TextProperty = AvaloniaProperty.Register<LostFocusTextBoxBindingBehavior, string>(
+        "Text", defaultBindingMode: BindingMode.TwoWay);
+
+    static LostFocusTextBoxBindingBehavior()
+    {
+        TextProperty.Changed.Subscribe(e => ((LostFocusTextBoxBindingBehavior) e.Sender).OnBindingValueChanged());
+    }
+
+    public string Text
+    {
+        get => GetValue(TextProperty);
+        set => SetValue(TextProperty, value);
+    }
+
+    /// <inheritdoc />
+    protected override void OnAttached()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.LostFocus += OnLostFocus;
+        base.OnAttached();
+    }
+
+    /// <inheritdoc />
+    protected override void OnDetaching()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.LostFocus -= OnLostFocus;
+        base.OnDetaching();
+    }
+
+    private void OnLostFocus(object? sender, RoutedEventArgs e)
+    {
+        if (AssociatedObject != null)
+            Text = AssociatedObject.Text;
+    }
+
+    private void OnBindingValueChanged()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.Text = Text;
+    }
+}