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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            switch(e.KeyData)
            {
             case Keys.Down:
                if (pictureBox1.Location.Y == 230)
                {
                    break;
                }
                this.pictureBox1.Location = new System.Drawing.Point(pictureBox1.Location.X ,pictureBox1.Location.Y + 10);
                toolStripStatusLabel1.Text = "Y: " + pictureBox1.Location.Y.ToString();
                break;
             case Keys.Up:
                if (pictureBox1.Location.Y == 0)
                {
                    break;
                }
                this.pictureBox1.Location = new System.Drawing.Point(pictureBox1.Location.X, pictureBox1.Location.Y - 10);
                toolStripStatusLabel1.Text = "Y: " + pictureBox1.Location.Y.ToString();
                break;
             case Keys.Left:
                if (pictureBox1.Location.X == 0)
                {
                    break;
                }
                this.pictureBox1.Location = new System.Drawing.Point(pictureBox1.Location.X - 10, pictureBox1.Location.Y);
                toolStripStatusLabel2.Text = "X: " + pictureBox1.Location.X.ToString();
                break;
             case Keys.Right:
                if (pictureBox1.Location.X == 280)
                {
                    break;
                }
                this.pictureBox1.Location = new System.Drawing.Point(pictureBox1.Location.X + 10, pictureBox1.Location.Y);
                toolStripStatusLabel2.Text = "X: " + pictureBox1.Location.X.ToString();
                break;
            }
        }
    }
}					

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int X = Math.Max(pb.Location.X - 10, 0);

// bzw. für rechts

int X = Math.Min(pb.Location.X + 10, Width - pb.Width);