If a web page tries to send you a pop-up when your blocker is turned on, an icon with a red 'x' will appear in your address bar.
#How to turn on pop up blocker in firefox windows
Click on the checkbox for Block pop-up windows to remove the checkmark, and then close the Preferences window. Click Done in the bottom right-hand corner. Select Safari -> Preferences from the menubar.
Under Pop-ups, select Allow all sites to show pop-ups.'Marked 1' If the button is greyed out Pop Up Blocker is on. 'Marked 1' Step 4: At the top you will see Blocked with a button beside it. To disable the pop-up blocker, uncheck the Block pop-up windows box. Scroll all the way down and choose Pop Up and Redirects. Click the Firefox menu in the right hand corner of the window.
Click the Settings button to disable pop-up blockers for specific sites.