ToggleLinks

If your press the command key on the Mac or the control key on the PC while clicking on a link to a tiddler, the tiddler will be opened as usual if it isn't already open, but if is open, it will be closed. It makes a handy way to review links without having to move the mouse around to re-close tiddlers.

You can make this behaviour the default under AdvancedOptions (you can override back to the normal behaviour with the same command/control key).