next_view_in_group.py

import sublime_plugin

class NextViewInGroup(sublime_plugin.WindowCommand):

    def run(self):
        currentGroup, currentViewIndex = self.window.get_view_index(self.window.active_view())
    	currentViews = self.window.views_in_group(currentGroup)
    	if currentViewIndex < len(currentViews) - 1:
    	  newView = currentViews[currentViewIndex + 1]
    	else:
    	  newView = currentViews[0]
    	  
        self.window.focus_view(newView)