You can resize the panes by pressing the 
ALT / 
Option key and dragging the split bar. (Just clicking the split bar will resize the topmost pane and the sub-pane of the dragged split bar only.)
Collapsing: Pressing the
ALT / 
Option key and double-clicking in a pane’s statusbar will collapse the pane so that the statusbar is displayed only and the pane above will fill the area. (Just double-clicking lets the pane above retain its size and the topmost pane will be enlarged.) A double-click on the statusbar of the topmost pane will collapse all panes below.
Expanding: Pressing the
ALT / 
Option key and double-clicking in a collapsed pane’s statusbar will expand the pane again – using space from the above pane. (If you just click it – without the 
ALT / 
Option key – the pane will be expanded using space from the topmost pane.) A double-click on the statusbar of the collapsed topmost pane will expand all panes below.
Minimizing: Double-clicking a pane’s split bar minimizes the pane or resizes it again.
ALT / Option key and dragging the split bar. (Just clicking the split bar will resize the topmost pane and the sub-pane of the dragged split bar only.) Collapsing: Pressing the
ALT / Option key and double-clicking in a pane’s statusbar will collapse the pane so that the statusbar is displayed only and the pane above will fill the area. (Just double-clicking lets the pane above retain its size and the topmost pane will be enlarged.) A double-click on the statusbar of the topmost pane will collapse all panes below.Expanding: Pressing the
ALT / Option key and double-clicking in a collapsed pane’s statusbar will expand the pane again – using space from the above pane. (If you just click it – without the ALT / Option key – the pane will be expanded using space from the topmost pane.) A double-click on the statusbar of the collapsed topmost pane will expand all panes below.Minimizing: Double-clicking a pane’s split bar minimizes the pane or resizes it again.