hi Behzad, yes , You can choose from a few choices. The -private-window command line option can be added to the shortcut you use to launch Firefox if you want it to start a Private Browsing window while still giving you the option to create a new ordinary window. If not, you can configure Firefox to only operate in Private Browsing mode. In Firefox's settings, under Privacy & Security, you can do that. You may activate Always use private browsing mode by scrolling down to History and choosing Use custom settings for history. As a side note, the purple mask does not appear in the browser windows or the new tab page if the Always use private browsing mode option is enabled. Hope this was useful.