Split a window from the keyboard
⌃⌥⌘→ splits right and ⌃⌥⌘↓ splits down. ⇧⌘Return zooms the focused pane; press it again to bring the others back.
How to do it
- Press ⌃⌥⌘→ to split the focused pane to the right, or ⌃⌥⌘↓ to split it downwards (⌃⌥⌘← and ⌃⌥⌘↑ split left and up).
- Each new pane browses on its own: open any folder in it.
- Press ⇧⌘Return to zoom the focused pane to the whole window.
- Press ⇧⌘Return again to bring the other panes back.
- Use ⌃⌥⌘= to make all panes the same size, or ⌃⌥⌘W to close the focused pane.
Shortcuts
⌃⌥⌘→⌃⌥⌘↓⇧⌘Return
More detail in the guide: Tabs, panes, and workspaces