The click-to-play implementation that landed in bug 711552 used the add-on icon (puzzle piece) in the doorhangers and popup-notification area. Since this is directly related to plugins, we should be using the plugin icon (lego block) in both of those locations. http://mxr.mozilla.org/mozilla-central/source/toolkit/themes/winstripe/mozapps/plugins/pluginGeneric-16.png for reference.
Click-to-Play Icon also does not have a Tool-tip
Created attachment 614620 [details] [diff] [review] Patch for bug Untested on OS X & Linux. I'll test it on OS X & Linux tomorrow, but the CSS is identical between the platforms so I don't expect any issues ;-)
Comment on attachment 614620 [details] [diff] [review] Patch for bug So I guess you'll also want to make this change for the icon in about:permissions. Feel free to make it here or in bug 711618, as you prefer.
I'll make the changes to about:permissions in bug 711618. https://hg.mozilla.org/integration/mozilla-inbound/rev/a038c8c200f5