We have an option to clear trailing whitespace (Format / Strip trailing whitespace) but it isn't always clear when to use it (because the trailing whitespace is invisible).

One thing the can be done is to colorize trailing white space to make it more visible (this idea is inspired by a similar feature in mercurial's colorized diffs).

Another option is put a hook on File / Save to scan for trailing whitespace and offer to remove it (this idea is inspired by the whitespace commit hook used in Python's own source code management).