Reload Gtk+ 3.0 theme

This is rather simple and effective:

1. While editing your theme open a Nautilus window
2. Kill Nautilus with killall, then open nautilus from the Terminal
3. Make your changes to the theme and kill nautilus again then relaunch it

You can see the changes you made witout doing anything difficult. Most elements that you change of the theme will reflect in Nautilus.

You can use this bash function to reload the theme without reloading the shell, you can add it to your ~/.bashrc file.

function reload_gtk_theme() {
  theme=$(gsettings get org.gnome.desktop.interface gtk-theme)
  gsettings set org.gnome.desktop.interface gtk-theme ''
  sleep 1
  gsettings set org.gnome.desktop.interface gtk-theme $theme
}

To use it, run:

$ reload_gtk_theme