bug#39649: 27.0.60; tab-line doesn't scroll

[Juri Linkov]

> Ok, but how does that impact the characters sizes being different?

It's hard to see the differences in characters sizes.
Do you see the same problem when using colors?
For example:

(defface tab-line '((t :background "red")) "")
(defface my-tab-line '((t :background "blue")) "")
(setq tab-line-format (propertize "abcdef" 'face 'tab-line))
(setq tab-line-format (propertize "abcdef" 'face 'my-tab-line))