It would be useful to allow a pane to zoom to the maximum available vertical space. The current zoom takes up the entire screen. This has its uses but is often more than necessary.

So, for example, a vertical zoom would cover one column in a standard two-column layout, and, more generally, cover any panes having a X offset and width equal to the pane from which the zoom is initiated.

The only way I can think of currently achieving something similar would be to move and resize various panes (then move them all back again), so a temporary vertical zoom would be handy.

I sadly can't comment to the practicalities of implementing this, so this is a mere suggestion of a feature tmux could have one day.