F&R is not a dockable window like the others. It can be shown via the Search->Find & Replace menu item, but it's not a Show/Hide toggle like View->Book Browser. The only way I know of to hide F&R, is to click the 'X' in its top left corner.
Could the Search->Find & Replace menu item and its shortcut be a show/hide toggle?
Long standing question: Why does Sigil's F&R allow me to tab into the 'current' file being edited and start inserting tab characters into the data rather than wrapping around the set of controls within the panel? The other EPUB editor is the same.
Maybe there does need to be a Give Focus to Find and Replace, rather having it entangled with Codeview.
I wrongly assumed a window had to be already on show to give it focus, but I like the fact that if it is hidden then giving it focus will show it.
The one thing lacking is a visual cue as to which window has keyboard focus… but Sigll is not alone in that regard.
BR