So, can we grant sudo to an already opened application ? I wish to first open an application as normal user and incase if i need root permissions on it i wish to grant su without restarting the application..

I tried opening an application and then type "sudo appname" in terminal, but that opens a new app window retaining normal user permissions on old app window.

Say, i want to check and edit /etc/apt/sources.list . I open a filemanager and go to the path and click on sources.list which opens a text editor with that file in view. If i feel i need to edit that, then i want to grant sudo to that instance of text editor rather than opening a new root text editor and browsing the entire path.