Not sure which version of Start11 you have, but in mine, in the Start11v2 config window:

and scrolling down, under the Advanced rounded corners settings...

Just curious. What version of Windows are you running? What version of RoundedTB are you running?

I received no screenshot from you. I'm not Support. My screenshots come from Start11v2. Again, what version of Start11 do you have? If you're not running Start11, but RoundedTB, Stardock doesn't support that third party software.

If you want a rounded task bar, download a trial copy of Start11v2 from Stardock and use my screenshots as a guide.

Just so you know, this was on reddit: https://www.reddit.com/r/windows/comments/16t2j7q/new_windows_update_broke_roundedtb/

RoundedTB has been archived at Github and isn't in MS store. It's dev isn't developing it further.

Hello,
I believe Niqui was requesting Start11 to have dynamic mode like RoundedTB, where the horizontal size of the actual taskbar can dynamic resize itself to fit all the taskbar icons in the center, correct Niqui? Something very similar to what ObjectDock QuickLaunch Dock can do. This has been requested before and I have submitted it to the Feature request thread for Support and Dev to review.

Thank you.
Basj,
Stardock Community Assistant.