Subject: Re: bug#51632: Emacs 28: posn-at-x-y fails to take a tab line into account.

From: martin rudalics <[email-masked]>
Date: Sat, 6 Nov 2021 19:50:23 +0100

> (i) emacs -Q
 > (ii) C-u C-h i <and info file> RET
 > (iii) M-: (point) ; Note this value
 > (iv) M-: (posn-at-x-y 0 18) ; Where 18 is the height of your default
 >    font.  Note that the second element of the result matches that from
 >    (iii)
 >
 > (v) M-x tab-bar-mode RET
 > (vi) M-: (posn-at-x-y 0 18) ; This returns the same as (iv).
 >
 > Because of the tab line, (vi) should return the symbol `header-line' in
 > its second element, not the same as (iv).  This is a bug.

I'm not sure I understand.  'tab-bar-mode' puts a tab bar on top of the
frame.  How is this related to 'posn-at-x-y' which, by default, deals
with the selected window?

martin