class CheckUrlsCommand(sublime_plugin.TextCommand):

    def run(self, edit):
        urls = []
selections = self.view.sel()
for selection in selections:
    urls.append(self.view.substr(selection))
messages = self.validate_urls(urls)
window = sublime.active_window()
window.show_quick_panel(messages, None, sublime.MONOSPACE_FONT)

def validate_urls(self, urls):
    messages = []
for url in urls:
    pass
Accessing the Quick Panel in a Sublime Text 2 Plugin