always move to the first/last non-whitespace character when the HOME/END keys are pressed.
move to the first/last non-whitespace character on the first press of the HOME/END keys and to the beginning/end of the line on the second press.
smart-home-end disabled.
move to the beginning/end of the line on the first press of the HOME/END keys and to the first/last non-whitespace character on the second press.