In Firefox 4 (FC15 intel) I find that the choice to display calendars appears as a blank white square box into which I can put a tick. In Chrome, the same type of check box appears as a slightly more sophisticated icon which will not click, however, other checkboxes that appear to look the same do check OK. The only one I have found that does not work is the choice of whether to deisplay entries from a particular calendar or not.
Brian -- users@sogo.nu https://inverse.ca/sogo/lists