title: How to close all open and hidden forms in C# with one button?
body: <p>I have a Splash Screen to my program.</p>
  
  <p>And when the splash end  , exec the code</p>
  
  <pre><code>this.Hide();
  frmLogin o = new frmLogin();
  o.show();
  </code></pre>
  
  <p>And it works but the splash screen go invisible and when i close the program by my custom exit button it's only closing the current form.
  But my splash screen is still hidden and appears the app name to task manager.
  How i can close that currently <em>opened</em> form and the <strong>invisible</strong> ones with my custom button ?</p>