A number of icons in various prompts / doorhangers / notifications need hidpi versions, so they don't look blurry (upscaled) on Retina displays. Arguably this list could be split up into separate bugs, but I think the changes for each is small enough that it can be done sanely in this one bug. But feel free to do further breakdown / split up / do followups if that makes sense. * Standard modal-window prompt icons (commonDialog.xul, eg as seen in the default browser prompt on startup) * addon confirm-install modal prompt - main /!\ icon - default icon for addons - out-of-scope for this bug: using a hires icon from the installee addon * addon post-install doorhanger ("installed successfully"), main icon * sync promo footer in some doorhangers, icon * "remember password" doorhanger (key-64.png) * doorhanger button's dropdown arrow to access secondary actions (panel-dropmarker.png) * default notification bars widgets? There are no @2x icons under toolkit/themes/osx/global/notification, but at least with the popup-blocker notification bar I see it using hidpi images. Is this just messy? * XUL(?) notifications (toolkit/themes/osx/global/alerts/notification-48.png) Although I'm not sure exactly how/if this gets used now?