def reverseAllLines():
	lines	= editor.getText().splitlines()
	lines.reverse()
	editor.setText(os.linesep.join(lines))

def reverseSelectedLines():
	import os

	staline	= editor.lineFromPosition(editor.getSelectionStart())
	endline	= editor.lineFromPosition(editor.getSelectionEnd())
	start	= editor.positionFromLine(staline)
	end		= editor.positionFromLine(endline)+editor.lineLength(endline)

	text	= editor.getTextRange(start, end)
	
	if text.endswith(os.linesep):
		eol = os.linesep
	else:
		eol = ''

	lines	= text.splitlines()
	lines.reverse()

	text	= os.linesep.join(lines)+eol

	editor.setSelection(start, end)
	editor.replaceSel(text)
	editor.setSelection(start, end)	#keep selection after replace


editor.beginUndoAction()
if editor.getSelectionStart() == editor.getSelectionEnd():
	reverseAllLines()
else:
	reverseSelectedLines()
editor.endUndoAction()