Whoops, sorry... there's a "readonly" state flag that disables direct editing of the entry (like with combobox) and just allows manipulation of the arrows. I've updated the PR to set that. I've also changed it so that the contents of the entry part isn't selected whenever the arrows are used (agreed, it looks ugly). Please give it a try and let me know.

p.s. I just checked, the entry's width configuration option works. You just have to remove the "fill=X" when the widget is packed. FWIW, I kept the previous layout to keep the patch as minimal as possible, under the assumption that other layout changes (here, on in general) were planned.