Anyone aware of a way to customize the appearance of the screen during fast user switching? I'd like to disable the background blur to make it look more like it did in Mavericks.
Yes, you can change the blurred background image on the login screen in Yosemite.
In root /Library/Caches (make sure you're not in the user ~/Library) you will find a file called: com.apple.desktop.admin.png. This is the blurred image that was created when you set your Desktop wallpaper.
Replace this file with any image you would like on your login page. Make sure to keep the permissions the same as the original file.
Hat Tip to Bobby T from Apple Support Communities: https://discussions.apple.com/message/26879262#26879262
oh yes ..you can change the login screen as well.. The howto provided in this link. The only 1 thing not mentioned there is to make sure that the 'permission' of the png file is set to be able to be read by the user. http://www.tekrevue.com/tip/custom-login-screen-wallpaper-os-x-yosemite/
Go to /Library/Caches, and modify the
com.apple.desktop.admin.png file. That contains an image for your login screen in Fast-User-Switching.
By default, the image looks like a place in Yosemite. Replace the image with an image of your choice that's not blurred.
This requires Admin privileges, though. Also, make sure you're not in ~/Library/Caches, you have to be in (Root)/Library/Caches. This image might be hidden.
To disable blurring, please read this tip http://www.mcelhearn.com/yosemite-tip-how-to-turn-off-the-annoying-translucency/