Windows lose focus, seemingly at random

Just had the same problem on Windows 8.1; here's how I found the issue fixed it:

1. Task Manager
2. Services Tab
3. Sort by status
4. Found a service that was running then stopping periodically - HP Connected Remote Service
5. Start menu
6. Type "Services"
7. Click "View Local Services"
8. Right click HP Connected Remote Service
9. Properties
10. Startup type: Disabled
11. OK
12. Fixed

The code to display the active process helped me solve my problem. I let the browser idle at an input field until it lost focus and checked the process ID. There was no active window title, which was perfect because that's what I was noticing -- it wasn't another window popping up, the current window simply lost focus.

I pulled up Task Manager, chose select columns, and added the PID column to the display. I sorted based on that column, tracked down the program and discovered it was app running in the system tray that I didn't need any longer. I gave it the heave-ho. Brilliant.

This was very useful for me. I modified the code a little bit so that it only prints when the active process switches, and it also prints the Process object itself. This helps because not all processes have an active window, so printing out the active window title may not help. The process that was stealing the focus for me turned out to be one of those background processes. 

(Credit to M Razavi, this is his code that I copy-pasted and added to)

If you want to compile it, it is C#. I did it in Visual Studio 2013.

Here is a version that I compiled on Windows 7, 64-bit.

https://docs.google.com/file/d/0B8J3t9FgHn13NU54Q29JS0dOZ3c/edit

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Diagnostics;

using System.Runtime.InteropServices;

using System.Threading;

namespace GetActiveProcess

{

    class Program

    {

        [DllImport("user32.dll")]

        private static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll")]

        private static extern Int32 GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

        private static Process GetActiveProcess()

        {

            IntPtr hwnd = GetForegroundWindow();

            return hwnd != null ? GetProcessByHandle(hwnd) : null;

        }

        private static Process GetProcessByHandle(IntPtr hwnd)

        {

            try

            {

                uint processID;

                GetWindowThreadProcessId(hwnd, out processID);

                return Process.GetProcessById((int)processID);

            }

            catch { return null; }

        }

        static void Main(string[] args)

        {

            Process old_process = null;

            while (true)

            {

                Process activeProcess = GetActiveProcess();

                if (old_process == null || (activeProcess != null && activeProcess.Id != old_process.Id))

                {

                    if (activeProcess.Id != Process.GetCurrentProcess().Id)

                    {

                        Console.WriteLine("PID=" + activeProcess.Id + "\nTitle=" + activeProcess.MainWindowTitle + "\n"+ activeProcess.ToString() + "\n");

                        old_process = activeProcess;

                    }

                }

                Thread.Sleep(10);

            }

        }

    }

}

I spent ages on this tonight and found my cure to be in the accessibility options:

control panel>ease of access>ease of access center>make the mouse easier to use

uncheck "activate a window by hovering over it with the mouse"

no idea how this got turned on but whenever I pushed the mouse to move the pointer out of the way for typing and it landed on another window it would shift focus to that window after a second or two

this is by design but I didn't switch it on myself maybe something else did?