A window frame will expand to fill the entire desktop when you
A. click the title bar button marked with a single square.
B. double-click the taskbar.
C. double-click the horizontal scroll bar.
D. click the title bar button marked with two overlapping squares.
A. Sometimes it is marked by outwards pointing arrows (<= =>) with the reverse (collapsing so as to not take up the whole screen) being in the same spot, marked by inwards arrows (=> <=)
