Allow non-breaking space to be added in WYSIWYG mode

At the moment there would appear to be no way to enter a non-breaking space in WYSIWYG mode.  When composing HTML pages (and for that matter, pages in any markup language), I make a point of using a non-breaking space to separate (for example) the indefinite articles "a" and "an" from the following word to prevent any risk of the articles becoming end-of-line orphans.  I appreciate that I could enter code-view mode and enter  , but that is hardly convenient, and HTML editors such as Dreamweaver recognise this and allow a non-breaking space to be entered as (e.g.,) Ctrl+Shft+space.