When the user double-clicks to start selection, the terminal will extend
the selection on word boundaries. It will treat characters included in spec
as parts of words, and all other characters as word separators. Ranges of
characters can be specified by separating them with a hyphen.
As a special case, if spec is NULL or the empty string, the terminal will
treat all graphic non-punctuation non-space characters as word characters.
When the user double-clicks to start selection, the terminal will extend the selection on word boundaries. It will treat characters included in spec as parts of words, and all other characters as word separators. Ranges of characters can be specified by separating them with a hyphen. As a special case, if spec is NULL or the empty string, the terminal will treat all graphic non-punctuation non-space characters as word characters.