Closing Split Panes

Hello. I’m a moron.

Let’s say I have the window horizontally split. In the top right of the upper pane, there’s a little cross-in-a-circle icon. If I click it, the upper pane closes and the lower pane takes over.

In the top right corner of the lower pane, there’s a little grey square icon. If I click it, the upper pane closes and the lower pane takes over.

So either way, the upper pane closes. So what’s an as-simple way of closing the lower pane?

Please bear in mind earlier information re: moron.

Thanks.

Ah. Just found the related topic in the Wish List forum (I didn’t check there initially as I assumed there was an obvious method I was missing). As you were.