Splits, windows, and tabs

Splits

Ex command	Effect
`:split` / `:sp`	Horizontal split: new window appears above the current one and gets focus
`:vsplit` / `:vsp` / `:vs`	Vertical split: new window appears left of the current one and gets focus
`:close` / `:clo`	Close the active window. Collapses parent split into the sibling. Last window of last tab = quit.

Or with the <C-w> chord:

Keys	Equivalent ex command
`<C-w>s` / `<C-w><C-s>`	`:split`
`<C-w>v` / `<C-w><C-v>`	`:vsplit`
`<C-w>c` / `<C-w><C-c>`	`:close`

Both forms work — held-Ctrl through both keys is equivalent to release-Ctrl-then-letter, the same way vim handles them.

Keys	Action
`<C-w>h` / `<C-w><C-h>`	Focus window to the left
`<C-w>j` / `<C-w><C-j>`	Focus window below
`<C-w>k` / `<C-w><C-k>`	Focus window above
`<C-w>l` / `<C-w><C-l>`	Focus window to the right
`<C-w>w` / `<C-w><C-w>`	Cycle to next window

The directional commands always step exactly one column/row at a time — they never skip past nearer windows. Within the target strip, the window that contains the cursor's screen position is selected. If the cursor sits exactly on a split boundary, the window above (or to the left) of the boundary wins.

Equalising splits

<C-w>= rebalances every split node in the current tab so each side gets space proportional to how many same-axis leaves it contains. Concretely: if you have three columns at the top level, each one gets ≈1/3 of the width regardless of how many rows are nested inside. Then within each column, the rows equalise among themselves.

Tabs

Ex command	Effect
`:tabnew` / `:tabe` / `:tabedit`	New tab with a scratch buffer (or `:tabnew <file>`)
`:tabnext` / `:tabn`	Cycle to next tab
`:tabprev` / `:tabp` / `:tabN`	Previous tab
`:tab new\|next\|prev`	Space-separated dispatcher form

Keymap:

Keys	Action
`gt`	Next tab
`gT`	Previous tab

A tab line appears at the top of the screen when there are 2+ tabs.

Per-window statusline

Every window has its own status row at the bottom of its rect — buffer name, dirty flag, cursor row:col. The active window's statusline is highlighted with a brighter background and shows the mode badge (NORMAL, INSERT, etc.); inactive ones are muted.

Split layout details

The split tree is a binary tree of horizontal / vertical splits with ratios. Splits are stored on each Tab. A Window is a leaf — buffer + cursor + viewport + last-known render size.

After every split / close, the tab's tree is rewritten:

:split replaces the focused leaf with Split { axis: H, ratio: 0.5, first: new_win, second: old_win } — new window goes on top.
:vsplit is the same but with axis: V, new window on the left.
:close removes the leaf and collapses the parent split into the sibling.

<C-w>= walks the tree and resets every ratio based on the same-axis leaf count of each subtree, as described above.