[KevinH]

Again, this is a change but NOT a bug. There is no guaranteed way have Sigil exactly restore itself and its dockwidgets back to what you had, once you have shrunk Sigil past its preferred size. It will require manual intervention. This happens with the previous version of Sigil as well, it is just the newer version needs 6 more pixels of horizontal space and allows more clip icons per clip bar.

Have you actually tried any of the ways mentioned previously to help conserve space? ie using the Sigil View menu to hide Table of Contents and Preview, hide Find and Replace, turn off one of the clips bars, or in Preferences change ui font or size, change icon size change, or change clips text, move clips to the second tool bar, etc.