Use the newer HTML5 "number" input type for inputs where users are just entering a number.
Use the HTML5 "url" input type for widget options that require a URL.
Placeholders! Placeholders! Placeholders! It's like free instructions on how to use form fields without having to explain it all out.
The `limit` argument for wp_get_archives() cannot be 0.
Use the "number" input type for the archives and authors widgets.
Introduce options for `single_text` and `multiple_text` for the topic count tooltips on the tag links. Preferably, we'd use the newer `topic_count_text` introduced into WP 3.9, but we can't send _n_noop() through the widget options form. Nevertheless, this is much preferable over having users create a topic count callback function.