Originally Posted by meme
Sounds like Qt5 at work again. Works fine on Linux... So when I detach the Book Browser and minimize my main window, the Book Browser minimizes with it.
But to attach it again you should be able to drag it from the titlebar and drop it somewhere in Sigil - to the left of the editing window, on top of the TOC window, etc. Its easiest to double-click to re-attach, but as that doesn't seem to work on XP it might not help.
Whe I initially launch Sigil the book browser is not visible, to make it visible I go to view and click book browser (a check mar appears) and then I can size and drag the book browser window all over the place but it will not dock. Double click does nothing.