Sublime Text Editor

import sublime, sublimeplugin, time

class HighlightWhitespace(sublimeplugin.ApplicationCommand):
    def onUpdate(self, view):
        region = view.findAll('^(\s+)')
        view.addRegions("HighlightWhitespace", region, "whitespace")

    def run(self, args):
        for window in sublime.windows():
            for view in window.views():
                self.onUpdate(view)