This is an issue Safari had a while ago. The keyboard shortcuts for changing tabs/views, cmd+shift+left and cmd+shift+right, conflict with the text-selection shortcuts to select text from the insertion point to the beginning or end of a line. Safari has since changed its shortcuts to cmd+shift+[ and cmd+shift+] to avoid the issue.
I ran into this while editing a description cell in the account view. Instead of selecting the text between the insertion point and the beginning of the line, as I expected, my edit was committed, and the view switched to the transactions view. Text selection shortcuts work as expected when the corresponding view changing shortcut is not available.
Yeah, I've been bitten by this as well.
(from ) [#59 state:fixed] Changed the arrow based shortcuts to  based shortcuts.
I wonder how people with non-US keyboards (which instead of having brackets in the right side of the keyboard, have accents and stuff) work with keyboard shortcuts. I tried switching to a french keyboard, and the shortcut, of course, wouldn't work.
However, Safari has the same problem, so I guess all apps have the same problem. Does it mean all people with non-US keyboards mainly use the mouse?
I haven't updated to Snow Leopard yet, but will soon. It sounds like Apple may have ("fixed")[http://hivelogic.com/articles/fix-broken-textmate-command-arrow-keys-in-snow-leopard/] this bug.
To actually answer your question, the keyboard shortcut listed in the Window menu changes to ctrl-tab and crtl-shift-tab when the keyboard layout is set to French. These both work with the US keyboard too, but they aren't listed in the menu.
I have to keep the arrow shortcuts around, after all. It really is a problem for foreign keyboards setup.
My first though would be to add some code on keyDown: of the main window which would check for arrow shorcut. I think that by having it there instead of the Main Menu, it would not conflict with the text shortcuts.
[milestone:id#49656 bulk edit command]
(from ) [#59 state:fixed] Added manual shortcuts to re-instate the old arrow based shortcuts (and these don't interfere with text based shortcuts!).