The box is there to copy the text, not to read it. Especially the HTML embed text can be arbitrarily long, if we want to make it visible, that would require a completely different UI, not tweaks to the current one.

CC Gilles & Pau - moving the reuse menu to the metadata panel would make this fixable.

(In reply to Tisza Gergő from comment #1)

The box is there to copy the text, not to read it. Especially the HTML embed
text can be arbitrarily long, if we want to make it visible, that would
require a completely different UI, not tweaks to the current one.

I don't follow this at all. Perhaps this is specific to my browser, but looking at attachment 16491, there is currently _plenty_ of room to expand the text area.

The text area should be larger by default and/or it should be resizable. The combination of it currently being both small and unable to be resized is unacceptably hostile to the user, in my opinion.

It could be made slightly larger, sure. It could not be made large enough to show the full HTML code for an average image - it tends to be fairly long. Resizing an element inside a container which has non-automatic dimensions will result in weird behavior.