[Therion] Updated XTherion editor side panel adjustment missing

The new look (v 6.0.5) XTherion editor seems to be missing the small button control that allows resizing of the side panel. I often like to make it quite large when editing objects with a long options string. Is resizing of the panel still available and I'm just not seeing it, or is it perhaps a bug? Therion 6.0.5 Windows 10 Home v 21H1 9043.1526