box comes up but it won't sign me in. am using same gmail acct and have added todoist.com to be accepted. could you please help me with this?
Within the Firefox's settings, please make sure that it is accepting third party cookies, is this was you are referring to when you say you added todoist.com as accepted?. Also, are you signing in with Google or with your username and password?
Which version of Firefox are you running? Do you have any Gmail Labs features enabled, such as Preview Pane?