If you create a file using gedit, which is configured to insert 4 spaces each time you press tab. Then for some reason you edit the file and some tabs get inserted (i.e. While editing on Windows). How can you replace those tabs back to spaces using gedit?
To do that you just need to use the replace form and search for: \t (backslash followed by t) then replace it with four spaces.
You can highlight, copy and paste a 'tab' from your file into the search and replace fields to achieve this in either direction tabs>spaces or spaces>tabs.