On a recent install of 10.10 i can't toggle with Alt+Shift between USA/Isr, even though i can toggle by pressing the language icon on the tool bar.
Any suggestions? Thanks
Have you checked the keyboard preferences?
Go to System --> Preferences --> Keyboard --> "Layouts" Tab --> Options
and find the option "Key(s) to change layout"
Related to the feature you mentioned, there's currently an open issue: https://bugs.launchpad.net/ubuntu/+source/control-center/+bug/36812
Enabling the Alt+Shift key to toggle between languages will cause that Ctrl+Shift+Tab (used to reverse cycle through open child windows/documents) does not work. At least that's my experience. Is it working for you?