What is best approach to get past browser asking users permission but open in seperate window?

I am developing a web application and are in the last phase to launch soon, but are running into a hurdle to present our web app to our users in a seperate window. Here's what we are trying to do: -when users login our web app on firefox browser (our chosen default browser) main window, we want web app to open in seperate window without requesting permission from user to allow window to open (an example to compare to is when web browser user, right clicks on any web page and goes to view source option, there is a seperate window that popups up displaying source) -we want to display seperate window for app in this presentation with no permissions requested to block user from viewing app What is the best approach to get past this? I appreciate any advice. Thank you