I'm using GNU Emacs 24.5.1 (x86_64-apple-darwin13.4.0, NS apple-appkit-1265.21) of 2015-04-10 on builder10-9.porkrind.org (from emacsformacosx.com) and I've got this annoying transparency going on and I don't know how to disable it. See attached image (it's not easy to spot but it's there).

Took a photo with my phone since it's not screen-grab-able

  • Can you describe what the problem is because it is hard to spot whatever is the spot you are referring to? Start with location of the spot. – Emacs User Jun 14 '15 at 23:55
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    Do you mean the transparency of the title bar? That is a OSX Mavericks feature, it is not emacs specific. – Jordon Biondo Jun 15 '15 at 1:01
  • I've added another photo (took it with my phone) since I realised the issue is not noticeable in the screenshot. I'm pretty sure now it's got nothing to do with Emacs since I can see the issue on other apps too but maybe someone knows about it. – Cezar Jun 17 '15 at 20:31
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    It's possible the alpha frame parameter is set to something other than 100 (full opacity). Try evaluating (set-frame-parameter (selected-frame) 'alpha 100) and let us know if you're still seeing the transparency issue. – Dan Jun 17 '15 at 20:43

If you're working on a MBPro Retina or Thunderbolt Display, or any display that uses in-plane switching (IPS) technology, your issue is likely image persistence.

I was experiencing the same problem on my Mac with all programs. I would close or hide a window (or Emacs frame), and I could see a very faint remnant of that window (frame). It also occurred when I switched OS X 'spaces.'

After putting it off for some time your question prompted me to finally investigate the issue. I would recommend Apple's article on Avoiding image persistence on Apple displays. The punchline:

To clear the persistent image, allow the screen saver to run for approximately as long as the image was being displayed.

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