Resize current pane width(holding second key is optional)
panes
// what it does
Ctrl+b Ctrl+Left / Ctrl+b Ctrl+Right run resize-pane -L / -R, widening or narrowing the active pane one column per press. Like the vertical resize these are -r (repeatable), so within repeat-time you can keep tapping Ctrl+Left / Ctrl+Right without re-issuing the prefix. The Ctrl modifier is required — plain prefix+arrow selects panes instead.
// shortcut
Ctrl + b→
Ctrl + bCtrl + →
Ctrl + b←
Ctrl + bCtrl + ←
// gotcha
A pane can't grow past its neighbor's minimum width, so at the edges the resize simply stops with no feedback. Manual widths are reset the next time you invoke a preset layout.