title: Change background image of form as soon as button on another form is clicked
body: <p>I am having two forms (<code>A</code> and <code>B</code>). In form <code>B</code> there are many buttons having different background image. On clicking any of the button I want to change the background image of form <code>A</code> to the background image of the button which was clicked instantly as it is always open behind the form.</p>
  
  <pre><code>formA mai = new formA();
  
  private void button1_Click(object sender, EventArgs e)
      {
          mai.BackgroundImage = button1.BackgroundImage;
      }
  </code></pre>
  
  <p>This is the code I am using although it changes the background image it doesn't change instantly but if I will open and close the form the background image will be changed.
  I don't need like that I need it to change instantly.</p>