expandselection.py

#coding: utf8
#################################### IMPORTS ###################################

# Sublime Libs
import sublime
import sublime_plugin

################################################################################

class ExpandselectionCommand(sublime_plugin.TextCommand):
	def run(self, edit, direction="left"):
		view = self.view
		for sel in view.sel():
			if direction == "left":
				if sel.b > sel.a:
					na = sel.b
					nb = sel.a
				else:
					na = sel.a
					nb = sel.b-1
			else:
				if sel.b < sel.a:
					na = sel.b
					nb = sel.a
				else:
					na = sel.a
					nb = sel.b+1
			
			view.sel().add(sublime.Region(na, nb))
		
		view.show(view.sel())

################################################################################

keys.sublime-keymap

[
	{
		"keys": ["ctrl+left"],
		"command": "expandselection",
		"args": {
			"direction": "left"
		}
	},
	{
		"keys": ["ctrl+right"],
		"command": "expandselection",
		"args": {
			"direction": "right"
		}
	}
]