vim

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6. Window resizing					*window-resize*

						*CTRL-W_=*
CTRL-W =	Make all windows (almost) equally high and wide, but use
		'winheight' and 'winwidth' for the current window.

:res[ize] -N					*:res* *:resize* *CTRL-W_-*
CTRL-W -	Decrease current window height by N (default 1).
		If used after 'vertical': decrease width by N.

:res[ize] +N					*CTRL-W_+*
CTRL-W +	Increase current window height by N (default 1).
		If used after 'vertical': increase width by N.

:res[ize] [N]
CTRL-W CTRL-_					*CTRL-W_CTRL-_* *CTRL-W__*
CTRL-W _	Set current window height to N (default: highest possible).

z{nr}<CR>	Set current window height to {nr}.

						*CTRL-W_<*
CTRL-W <	Decrease current window width by N (default 1).

						*CTRL-W_>*
CTRL-W >	Increase current window width by N (default 1).

:vertical res[ize] [N]			*:vertical-resize* *CTRL-W_bar*
CTRL-W |	Set current window width to N (default: widest possible).

You can also resize a window by dragging a status line up or down with the
mouse.  Or by dragging a vertical separator line left or right.  This only
works if the version of Vim that is being used supports the mouse and the
'mouse' option has been set to enable it.