Right clicking – Mac or PC (or Control clicking on a Mac) on a photo in any Lightroom module, will almost always (there are a few exceptions where it doesn’t) call up a contextual menu window of options. But there’s something unexpected that can happen and it usually happens a few days after I teach a student about contextual menus. I get a distress call that the Lightroom Basic panel (or some other sub-panel) is missing and they’re sure it was there just a minute ago. This can happen when your cursor ends up over the main left or right side panels while right clicking. Then what you get is the contextual menu for hiding and revealing the sub-panels. In the screen capture above, I was too far right when I right clicked in the Develop module instead of over the photo. This brought up the hide/reveal list of sub-panels. Click somewhere over that list to try and close the contextual menu window and one of your sub-panels will usually disappear.
And now that you have inadvertently hidden a panel from the group, here’s the way to get it back:
Right click on any of the sub-panel names to return to the contextual menu window in the module where the sub-panel is missing. In the screen capture to the left, notice that the missing sub-panel in the list is unchecked. Simply click on the missing item. This will immediately close the window and return the missing panel.
Should you accidentally call up this menu again at some point (it happens to everyone who uses contextual menus!), instead of a random mouse click to close out the window, press the ESC (aka Escape) key of your keyboard (it’s on the top left). This will close the contextual window without clicking and you will avoid accidentally hiding a panel.
And, why does Lightroom have this contextual menu in the first place? It’s for hiding panels you don’t use or rarely use. However, it seems to me that, more often than not, you end up hiding a frequently used panel.