Subject: bug#50798: 28.0.50; Tab line close button is off-center until it is highlighted with the mouse

From: Eli Zaretskii <[email-masked]>
Date: Thu, 07 Oct 2021 13:13:37 +0300

> From: Juri Linkov <[email-masked]>
> Cc: [email-masked],  [email-masked],  [email-masked]
> Date: Wed, 06 Oct 2021 10:16:27 +0300
> 
> It seems this test case exposes the problem.
> The face 'test-highlight' just inherits from 'test-tab',
> but hovering over the image shifts it upwards outside of the view.
> The test uses the header-line to show that the problem is the same
> for both the tab-line and the header-line.
> 
> (defface test
>   '((t :height 2.0))
>   "")
> 
> (defface test-tab
>   '((default :inherit test)
>     (t :box (:line-width 1 :style released-button)))
>   "")
> 
> (defface test-highlight
>   '((default :inherit test-tab))
>   "")
> 
> (setq header-line-format
>       (list (propertize " + "
>                         'display '(image :type xpm
>                                          :file "tabs/new.xpm"
>                                          :margin (2 . 0)
>                                          :ascent center)
>                         'face 'test-tab
>                         'mouse-face 'test-highlight)))

Thanks, but I'm not sure I understand what you expected and why.  the
face 'test' is defined to be twice the width of the default face.  The
face test-highlight inherits from it, but the 't' case doesn't change
the :height attribute, so it ends up having the same height, just with
the :box attribute.  That's why it looks bad on the header line: its
height is greater than that of header-line.

What did you expect to happen with these definitions of faces?