This commit removes the ".not(can-edit)" selector filter from
insert_tip_box. We do not require this selector filter because
this class is only used for emoji-settings and we already do not
prepend tip in emoji-settings page from this function and we handle
it separately.
As this class is only used for this purpose we can also remove this
class from emoji_settings_admin.hbs.
We already know which list widget a `<th>`
tag is associated with when we set up the
event handler, so it's silly to read data
from the DOM to find that widget again
when the handler runs.
This commit eliminates a whole class of possible
errors and busy work.
This adds a preview of the uploaded emoji image while uploading custom
emoji right below the upload form.
Modified upload_widget.build_widget() to take in the preview
span text and image. In case a parameter isn't passed
for preview text, it defaults to null and the snippets in
build_widgets() related to preview don't run.
Fixes#9229.
Styling tweaked by tabbott.