Notify Ubuntu/Gnome using script that application is busy to prevent power off

When using "Power Off" action in Gnome if there are some GUI applications with unsaved changes (for example, text editor) there will be label "Some applications are busy or have unsaved work". I am looking for a way to set this "unsaved" status from command line. So I can integrate it into my workflow when I'm using tmux/neovim, to not accidentally power off PC when I have some sessions opened.