(Feature request) Option to close any of the panes from 2 open panes

[sanskarfc]

Describe feature

If 2 panes are open, the option to close the pane is only available for pane 2 (on the right).

It would be a bit more intuitive if we should be able to close any of the 2 panes and the other pane occupies the central position.

Additional Information

If needed, I can take this up and put up a small PR. Thanks!

[zadam]

It's not a bad idea, but what I'm worried about is that addition of another button would make the UI more bloated / confusing...