Use external text editors
You can open files for editing in the default text editor for your system: Notepad on Windows and vi on Linux and macOS. To open the file you are currently viewing in an external editor, select Tools > External > Text > Edit with Notepad or Edit with vi, depending on your system.
Qt Design Studio looks for the editor path in the PATH environment variable of your operating system.
See also Use external tools.
Available under certain Qt licenses.
Find out more.