Reproduce steps:

1. Emacs -Q

2. M-x eval-expression `(set-face-attribute 'tab-line nil :height 1)`

3. M-x tab-line-mode

The tab-line-mode is enabled but the close-button shows a white rectangle.

Also the *Messages* buffer printed: Invalid image size (see ‘max-image-size’) [12 times]

Try `(insert (icon-string 'tab-line-close))` in a buffer and Evaluate Last S-expression, it can show the icon 'x'.

Background:

Emacs' default tab-line is too small, I used the method to adjust tab-line height in Emacs 29.3 and it works very well.

This issue only occurs on Emacs 30.1.

Environment

Emacs 30.1 on Windows 10.

Thanks.

Best regards,
Siyuan Chen