Tool windows like previous versions

In previous versions of CLion I could have the Structure and Debug tool windows flip back and forth. If one was up, the other was minimized. This was done by unchecking a "Split" option in the option menu for the tools windows. Now that is gone and so when the Debug windows comes up it splits with the structure window.

How do I get the old functionality back, where only one or the other will be up at a time?

Note: "Dock Unpinned" doesn't do it because the windows disappear when they are not active. Setting Structure to Dock Pinned and Debug to Undock doesn't work because making the Debug window large enough to be useful blocks the main code window.