To resize windows, hover your cursor over any dark dividing line between sections to display a two-way arrow that moves that boundary either up and down, or left and right.
Within certain views, you can display or hide a drawer, indicated by a dark gray banner that turns lighter gray at cursor hover. Double-click to close the drawer so only the banner is displayed; double-click again to re-open it. Click and drag the banner to move the banner up or down to resize the areas within the view.
Drawer Open
Drawer Closed