copy sublime text3's current selection into clipboard. Inspired by iterm2's `copy on select` feature.

select2clipboard.py

import sublime, sublime_plugin

class Copy_on_select(sublime_plugin.EventListener):
     def on_selection_modified(self, view):
        for region in view.sel(): 
            if not region.empty():  
                print(view.substr(region))  
                view.run_command('copy')

# for debugger:
print("selection modified") # shown in console panel(ctrl+`)
sublime.message_dialog("selection modified")