format_set_underline

@brief Turn on underline for the format:

@param format Pointer to a Format instance. @param style Underline style.

Set the underline property of the format:

@code format_set_underline(format, LXW_UNDERLINE_SINGLE); @endcode

@image html format_font_underlined.png

The available underline styles are:

- #LXW_UNDERLINE_SINGLE - #LXW_UNDERLINE_DOUBLE - #LXW_UNDERLINE_SINGLE_ACCOUNTING - #LXW_UNDERLINE_DOUBLE_ACCOUNTING