Set window OnTop in running programs from C#

Introduction

You can set running programs to ontop of window stack (application float above other windows).

Using the code

I used Platform Invoke method call SetWindowPos to set selected window to ontop of others and System.Runtime.InteropServices to get Running Applications.

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace OnTop
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool SetWindowPos(IntPtr hWnd,
            int hWndInsertAfter, int x, int y, int cx, int cy, int uFlags);

        private const int HWND_TOPMOST = -1;
        private const int HWND_NOTOPMOST = -2;
        private const int SWP_NOMOVE = 0x0002;
        private const int SWP_NOSIZE = 0x0001;
        public Form1()
        {
            InitializeComponent();
            LoadProcesses();   
        }
        private void LoadProcesses()
        {
            //Getting all the process
            listBox1.Items.Clear();
            Process[] processes = Process.GetProcesses();
            this.listBox1.DisplayMember = "MainWindowTitle";
            this.listBox1.ValueMember = "MainWindowHandle";
          
            foreach (Process process in processes)
            {
                //Adding only process which has got Window Title.
                if (process.MainWindowTitle.Length >= 1)
                {
                    this.listBox1.Items.Add(process);
                }
            }
        }
        private void btnOntopSet_Click(object sender, EventArgs e)
        {
            if (this.listBox1.SelectedIndex != -1)
            {
                Process process = this.listBox1.SelectedItem as Process;
                SetWindowPos(process.MainWindowHandle,
                    HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
            }
        }

       private void btnRefresh_click(object sender, EventArgs e)
        {
            LoadProcesses(); 
        }

       private void btnOntopSetDefault_click(object sender, EventArgs e)
        {
            if (this.listBox1.SelectedIndex != -1)
            {
                Process process = this.listBox1.SelectedItem as Process;
                SetWindowPos(process.MainWindowHandle,
                    HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
            }
        }
    }
}

Points of Interest

private static extern bool SetWindowPos(IntPtr hWnd,
           int hWndInsertAfter, int x, int y, int cx, int cy, int uFlags);

Changes the size, position, and Z order of a child, pop-up, or top-level window. These windows are ordered according to their appearance on the screen. The topmost window receives the highest rank and is the first window in the Z order.

more info about SetWindowPos()

http://msdn.microsoft.com/en-us/library/windows/desktop/ms633545%28v=vs.85%29.aspx