title: How can I remove the "blur" effect that Cocoa adds to transparent sheets?
body: <p>By default, Cocoa adds a background blur effect to transparent and semitransparent modal sheets when they are applied to a window. I would like to disable the blur effect. How would I go about doing it?</p>
  
  <p>I have created a custom sheet (a subclass of NSWindow with a transparent background and some controls in it). I am able to display it using the standard <code>beginSheet</code> method as follows:</p>
  
  <pre><code>[NSApp beginSheet:myCustomSheet
     modalForWindow:mainWindow
      modalDelegate:self
     didEndSelector:...];
  </code></pre>
  
  <p>The sheet displays fine, but everything behind it is blurred.</p>
  
  <p><strong>Note 1:</strong> I am writing a completely customized user interface for a touch screen / kiosk type app, so none of the usual Apple user interface guidelines apply.</p>
  
  <p><strong>Note 2:</strong> I <em>do</em> want to see what is underneath the sheet. As <a href="https://stackoverflow.com/questions/3420232/how-can-i-remove-the-blur-effect-that-cocoa-adds-to-transparent-sheets/3420783#3420783">SirRatty</a> pointed out, it is possible to block out the blurred portion by filling in the background. In my case, I want to have the background show through, just without appearing blurred.</p>