C#

using System.Collections.Generic;
using System.Runtime.Serialization;
using System.Windows.Forms;

namespace ?????????????
{
    [DataContract]
    public static class PanelToNode
    {
        [DataMember]
        private static Dictionary<string, string> PanelNameToTreeNodeKey;

        //static ctor
        static PanelToNode()
        {
            PanelNameToTreeNodeKey = new Dictionary<string, string>();
        }

        public static TreeNode GetCurrentNode(Panel pnl)
        {
            // => Treenode
        }

        public static Panel GetCurrentNode(TreeNode node)
        {
            // => Panel
        }

        public static void Serialize(string filepath)
        {

        }

        public static void DeSerialize(string filepath)
        {

        }'

    }
}

using System.Windows.Forms;

namespace YourNameSpace
{
    public class OuterClass
    {
        public OuterClass(int someInt)
        {
            SomeOuterInt = someInt;
        }

        public int SomeOuterInt { set; get; }

        public void SayWhat()
        {
            MessageBox.Show("Outer What");
        }

        public class InnerClass
        {
            public InnerClass(int someInt)
            {
                SomeInnerInt = someInt;
            }

            public int SomeInnerInt { set; get; }

            public void SayWhat()
            {
                MessageBox.Show("Inner What");
            }
        }
    }
}

// requires declaring you are using 'YourNameSpace

OuterClass outerClass = new OuterClass(42);

OuterClass.InnerClass innerClass = new OuterClass.InnerClass(24);

outerClass.SayWhat();
innerClass,SayWhat();

OuterClass outerClass = new OuterClass(42);

outerClass.InnerClass.SomeInnerInt = 108;

// Error	CS0572	'InnerClass': cannot reference a type through an expression

// or this: innerClass.outerClass.outerInt = 99;

public class Game
{
    public Game()
    {
        Inventory = new GameInventory();
    }
    
    public GameInventory Inventory { get; }
}

public class GameInventory
{
    public object GetObject()
    {
        return ...
    }
}

...

Game game = new Game();
object x = game.Inventory.GetObject();

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace YOURNAMESPACE
{
    public static class ControlMovableExtensions
    {
        private static Control currentControl = null;

        private static Control currentContainer= null;

        private static List<Control> MovableControls = new List<Control>();

        private static Rectangle ClippingRect;

        private static Rectangle ContainerRect;

        private static Point lastGoodLocation;

        private static Point nextLocation;

        private static int mdx, mdy;

        private static bool IsMouseUp = true;

        // experiment with these settings
        private static bool UseClipping = false;
        private static bool UseCapture = false;

        public static void SetMovable(this Control control)
        {
            if (MovableControls.Contains(control))
            {
                throw new ArgumentException("control already movable");
            }

            MovableControls.Add(control);

            control.MouseDown += ControlOnMouseDown;
            control.MouseUp += ControlOnMouseUp;
        }

        public static void RemoveMovable(this Control control)
        {
            if (! MovableControls.Contains(control))
            {
                throw new ArgumentException("control is not movable");
            }

            control.MouseDown -= ControlOnMouseDown;
            control.MouseUp -= ControlOnMouseUp;
        }

        private static void ControlOnMouseMove(object sender, MouseEventArgs e)
        {
            if (IsMouseUp) return;

            nextLocation =  new Point(currentControl.Left + e.X - mdx, currentControl.Top + e.Y - mdy);

            if (ContainerRect.Contains(new Rectangle(nextLocation, currentControl.Size)))
            {
                lastGoodLocation = nextLocation;
            }

            currentControl.Location = lastGoodLocation;
        }

        private static void ControlOnMouseUp(object sender, MouseEventArgs e)
        {
            IsMouseUp = true;

            currentControl.MouseMove -= ControlOnMouseMove;

            if (UseClipping) Cursor.Clip = Rectangle.Empty;

            if (UseCapture) currentControl.Capture = false;

            currentControl = null;
        }

        private static void ControlOnMouseDown(object sender, MouseEventArgs e)
        {
            currentControl = sender as Control;

            if (currentControl == null)
            {
                throw new ArgumentException("control is null");
            }

            currentContainer = currentControl.Parent;

            ContainerRect = currentContainer.ClientRectangle;

            lastGoodLocation = currentControl.Location;

            mdx = e.X;
            mdy = e.Y;

            if (UseClipping)
            {
                ClippingRect = currentContainer.RectangleToScreen(currentContainer.ClientRectangle);
                Cursor.Clip = ClippingRect;
            }

            if (UseCapture) currentControl.Capture  = true;

            currentControl.MouseMove += ControlOnMouseMove;

            IsMouseUp = false;
        }
    }
}

pr1mem0ver wrote:

he is probably saying that his editbox doesn't catch the backspace button

if (e.KeyChar == Convert.ToChar(8))

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.