Pressing the Tab key on your keyboard can be a useful way to navigate within grids in Rally. However, if you are using the MAC OS X system, you will need to ensure that a specific keyboard setting is enabled when using either Firefox or Safari browsers.
Open the browser, then click System Preferences > Keyboard > Keyboard Shortcuts > Full Keyboard Access. Select the All Controls setting.
Open the browser, then click System Preferences > Advanced. Select the Press Tab to highlight each item on a webpage option.