Can't edit pen style

I have been unable to edit pen styles. I can add a pen style, but I am unable to rename the style or change the sizes or smothness. Nothing happens when I double click in the appropriate boxes.

Any suggestions are appreciated!

Could be a graphics glitch on a graphic card that is less than optimal. Try updating your card’s driver and try changing the renderer in the TBS preferences’ “Display” tab (requires a software reboot to notice the change).