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Update to FF 23 changed resolution from 1600x900 to 1280x720, increased window size, and made text big and images and videos blurry

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After upgrading to ff 23 from ff21 on my Windows 8 ultrabook laptop, the browser window blew up to fill the entire screen. Web pages stopped displaying properly - text is big, but images are blurry, including those on the ff toolbar, and videos are pixelated and unviewable.

I tried the layout.css.devPixelsPerPx fix - it didn't work. The text became unreadably small instead.

I noticed that javascript window resolution in Firefox 23 is showing a resolution of 1280x720 instead of the 1600x900 that it should be. How do I get FF 23 to display in 1600x900 resolution?

After upgrading to ff 23 from ff21 on my Windows 8 ultrabook laptop, the browser window blew up to fill the entire screen. Web pages stopped displaying properly - text is big, but images are blurry, including those on the ff toolbar, and videos are pixelated and unviewable. I tried the layout.css.devPixelsPerPx fix - it didn't work. The text became unreadably small instead. I noticed that javascript window resolution in Firefox 23 is showing a resolution of 1280x720 instead of the 1600x900 that it should be. How do I get FF 23 to display in 1600x900 resolution?

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Yes, the screen.width and screen.height are adjusted for the device pixel ratio based on your zoom level. (Demo page: http://dev.jeffersonscher.com/resolution.html)

It sounds as though your Firefox 23 is picking up a Windows setting of 125% zoom. If you change layout.css.devPixelsPerPx to 1.0, Firefox should display at your display's native resolution instead of your Windows resolution (100% instead of 125%). This will indeed make the text in the toolbar area a lot smaller, but the content area should look the same as Firefox 21. Does it look a lot different? How much zoom (e.g., Ctrl+) is needed to make it look like you remember?

Meanwhile, you can use this extension to adjust the toolbar area if you stick with the 1.0 setting: Theme Font & Size Changer. Clicking its icon and changing the font size from "Normal" to 14 or 15 usually works pretty well. Once you re done with your adjustments, you can use the Customize feature to take its icon off the toolbar. (Customize Firefox controls, buttons and toolbars)