To the user, this looks like a disfunctional thing (usually greying out
is used for props having no effect).
The greying out is caused by
{rB8b7cd1ed2a17e40661101eea4adae99e8e3d02e9}.
Above commit disabled the direct renaming of images in the
`TEXTURE_UL_texpaintslots` UIList (and instead displays the texture slot
directly as a prop -- which has its `PROP_EDITABLE` flag cleared)
(from the commit message):
> A limitation of this patch is that is isn't possible anymore to rename
images directly from
> the selection panel. This is currently allowed in master. But as
CustomDataLayers
> aren't ID fields and not owned by the material supporting this wouldn't
be easy.
To work around the UI confusion (but still keep the non-editable nature
of the property), now just display this as a label.
Maniphest Tasks: T101334
Differential Revision: https://developer.blender.org/D16138