How To get The Focused Control

Import namespaces

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

Win API

[DllImport("user32.dll")]
static extern IntPtr GetFocus();

Use

Control focused = null;
IntPtr handle = GetFocus();
if (handle != IntPtr.Zero)
{
    focused = Control.FromHandle(handle);
}

messageBox(focused.Name);