Are you sure that all Private Browsing mode tabs and windows are closed?

If there is still a PB mode tab or window open then the cookie jar used by PB mode is still present.

mace2 said

When I log into Gmail with Firefox 39 for the Mac sha256 - 7da80d615390fc65f0f5540ac2fbaa6e5d8e8e0b and close the tab and then immediately open gmail again it automatically logs me into my Gmail account even though I am using private browsing. Private browsing is not suppose t maintain any information so how is it able to log into my Gmail account without my password being entered?

When I perform the test a second time.

1) I close Gmail tab 2) open another tab and type gmail.com It immediately logs me into my Gmail account without a password or accoun name. this is all done in Private browsing mode

I'm not sure how Private Browsing mode works on Mac because you can close all tabs, but still have the Firefox application running (the menu bar is there), so it is likely that you haven't ended the PB mode session. You may have to close and restart Firefox to get rid of the cookies that make the website remember you. Closing tabs doesn't seem to be sufficient.

You can use an extension to get Private Browsing mode support per tab.

• Private Tab: https://addons.mozilla.org/firefox/addon/private-tab/
• Private Browsing mode tabs get a dashed underline
• You can toggle Private Browsing mode on/off via the right-click context menu of a tab

The private browsing only works for a single tab not multiple. This is deceptive since the private browser mask symbol appears in the upper right corner suggesting all tabs are protected by private browsing when only the first open tab is.