Horizontal Slider edit control

I have a couple of horizontal linear bar sliders and when I click on them for editing, the text becomes left justified even though it is centered when the slider is not in "Edit" mode. I have tried changing the text position but it seems to have no effect at all.  It is a bit disconcerting because the text is centered until you click on it and then it becomes left justified for editing. I would like to have it stay centered but I can't figure out how to do it.

Yeah, the TextEditor doesn't have centred justification yet - will add this, it's in our backlog..