strut problem

[Werner LEMBERG]

Consider this input.

```
\version "2.23.81"

#(define-markup-command (strut layout props)
   ()
   #:properties ((baseline-skip))
   (ly:make-stencil ""
                    empty-interval
                    (cons (* -0.3 baseline-skip)
                          (* 0.7 baseline-skip))))

{
  \override TextScript.show-horizontal-skylines = ##t
  e'4^\markup { "a" }
  e'4^\markup \concat { \strut "a" }
}
```

Why is the vertical extent of the strut ignored?


    Werner