color the header of a listbox

@Jared Feder shared in April 25th, 2017 a customized listbox (see in older posts) and it is like what I am looking for except when the sum of the column widths of the listbox is larger than the listbox width. The listbox respond correctly to the scrollbars changes but not the canvas with the headings that remains static.
Did you or any other memeber of the forum, had done an aditional work over this customized listbox in order to solve this. If so, do you mind to share ?
Thanks