For `focused` elements in widgets, also auto-select current text where possible

@devoncarew 

`<textarea>` and `<input type="text">` and possible some others support `select()` in addition to `focus()`, which also selects the current text in the element. Make use of that.

This is a small thing which I've added by accident while addressing a bug which didn't actually call for it, but it's still potentially useful.
Yes, I've checked, and it was indeed possible. I had doubts about `<input>`, since it's such a weird thing that can not only be an input box, but also a check box, a button etc., for which select() doesn't make sense as defined, but it seems to just fall back to focus() in those cases.