User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:40.0) Gecko/20100101 Firefox/40.0 Build ID: 20150510030207 Steps to reproduce: Firefox 40 finally adds some High-DPI toolbar icons (e.g. used at 200% system-level scale) for main GUI (Australis menu is still entirely Low-DPI though). But the Downloads button is buggy: by default, the Downloads button is High-DPI, but once pressed/clicked, it immediately gets blurry Low-DPI as in previous Firefox versions. Tested with the latest nightly build 20150510030207. High-DPI icons themselves have been added in the build 20150410030204. Actual results: High-DPI Downloads button gets Low-DPI once pressed/clicked. Expected results: High-DPI Downloads button should be permanently High-DPI regardless of whether is has been pressed/clicked.

Same with the new build 20150511030203.

This bug should not have been duped. We should get this fixed in Firefox 40 so it rides along with bug 1147702.

[Tracking Requested - why for this release]: Firefox 40 introduced hires icons for Windows on the toolbar, it looks like this one was missed.

Adding a tracking flag for firefox40.

(In reply to comment #5) > Firefox 40 introduced hires icons for Windows on the toolbar, it looks like > this one was missed. To be clear: the high-DPI icon for Downloads button is NOT missing in Fx40+, the button IS high-DPI by default, but becomes low-DPI after it has been pressed (after browser restart, the button is high-DPI again until it's pressed). Probably a purely stylesheet-level issue (like if the button was a link, and the `:visited` link had the low-DPI icon assigned).

Apparently the bug reason is that once Downloads button (`#downloads-button`) is pressed, it gets invisible (`display: none`) due to `indicator` attribute (see "browser\chrome\browser\content\browser\browser.css" in Firefox folder or "chrome://browser/content/browser.css" as URL): #downloads-button[indicator]:not([cui-areatype="menu-panel"]) > image.toolbarbutton-icon, #downloads-button[indicator][cui-areatype="menu-panel"] > #downloads-indicator-anchor { display: none; } and instead of it, the `#downloads-indicator-anchor` element is dynamically inserted. This new element contains the `#downloads-indicator-icon` element, and this element has only low-DPI icon ("chrome://browser/skin/Toolbar.png", not "chrome://browser/skin/Toolbar@2x.png") assigned via styles ("browser\chrome\browser\skin\classic\browser\browser.css"): #downloads-indicator-icon { background: -moz-image-rect(url("chrome://browser/skin/Toolbar.png"), 0, 198, 18, 180) center no-repeat; min-width: 18px; min-height: 18px; } toolbar[brighttext] #downloads-button:not([attention]) > #downloads-indicator-anchor > #downloads-indicator-icon { background: -moz-image-rect(url("chrome://browser/skin/Toolbar-inverted.png"), 0, 198, 18, 180) center no-repeat; } #downloads-button[attention] > #downloads-indicator-anchor > #downloads-indicator-icon { background-image: -moz-image-rect(url("chrome://browser/skin/Toolbar.png"), 18, 198, 36, 180); } toolbar[brighttext] #downloads-button[attention] > #downloads-indicator-anchor > #downloads-indicator-icon { background-image: -moz-image-rect(url("chrome://browser/skin/Toolbar-inverted.png"), 18, 198, 36, 180); }

Thanks for the investigation. Would you like to submit a patch to fix this?

Unfortunately I have no experience of creating patches for Firefox (nor is my XUL knowledge deep enough), but hopefully based on the info I've provided, it will be trivial for a Mozilla developer (probably that who has already added high-DPI icons in their current state) to create the patch. Thanks.