* lisp/cus-edit.el (custom-comment-show): Add docstring. Save the
widget value in the :shown-value property, before redrawing.
(custom-variable-modified-p): New function, to complement the return
values of custom-variable-state.
(custom-variable-state-set): Use it.
(custom-face-value-create): Add children to the custom-face widget
before setting the state, to be able to check for user edits.
(custom-face-state-set): Check for user edits before calling
custom-face-state (bug#5358).
* test/lisp/custom-tests.el
(custom-test-show-comment-preserves-changes): New test.
* test/lisp/custom-tests.el (custom--test-user-option)
(custom--test-variable): New variables.
(custom--test-theme-variables): New test.
* test/lisp/custom-resources/custom--test-theme.el (custom--test):
New file.
Update some other copyright years automatically, by running:
Run 'UPDATE_COPYRIGHT_YEAR=2019 \
UPDATE_COPYRIGHT_USE_INTERVALS=1 \
UPDATE_COPYRIGHT_MAX_LINE_LENGTH=79 admin/update-copyright'
followed by 'admin/merge-gnulib'.
For discussion, see thread starting at
https://lists.gnu.org/archive/html/emacs-devel/2018-05/msg00222.html.
* lisp/custom.el: (custom-available-themes): Use directory-files
instead of performing arbitrary wildcard expansion in file names.
(custom-theme--load-path): Document return value.
* test/lisp/custom-tests.el: New file.
(custom-theme--load-path): New test.
