I now have the following Vim script in place; I decided to create a highlight group called CursorLineNC, When you leave a window, it sets a match on the current line. When you enter it again, it removes it. I always have 'cursorline' on, so this works well (the match supersedes the cursorline setting) unless scrollbind or cursorbind are set, where you can see the current cursor line in the other window moving, while the CursorLineNC highlighted line remains where it was. Frankly, I'm not sure I consider that a bug because it's a visual indicator of where I was when I was last in the window, even if that's not where I will be the next time I go in there; otherwise, it could be turned off in an OptionSet autocommand if cursorbind/scrollbind are turned on.
def HighlightCurrentLine(): void
w:matchLine = matchadd( 'CursorLineNC', '\%' .. line( '.' ) .. 'l' )
enddef
def ClearCurrentLineHighlight(): void
if ( exists( 'w:matchLine' ) )
matchdelete( w:matchLine )
unlet w:matchLine
endif
enddef
augroup highlightCursorLine
au!
au WinLeave * HighlightCurrentLine()
au BufEnter,WinEnter * ClearCurrentLineHighlight()
augroup END
All the best,
Salman