title: How to detect current focused textbox in C#?
body: <p>I have 20 textbox and 40 buttons within a form, I would like to click any of 40 buttons then it will insert the value to the current focused or active textbox of 20 textbox.</p>
  
  <p>But I don't know how to handle this in C#, please any idea would be great?</p>
  
  <p>Thanks,</p>