Lightroom Panel Tips and Tricks
The user interface in Adobe Lightroom is made up of panels that are highly configurable for various needs. Sometimes they seem to configure themselves accidentally too. Here are some tips and tricks to help you understand how they work.
The basics of panels are fairly straightforward. Individual panels are arranged into groups, one on the left and one on the right hand side of the screen. There's also the Module Picker across the top and the Filmstrip along the bottom. The display of each of these four main groupings can be turned on and off individually to provide more screen real estate for your actual image and what you are working on. To do so, go to Window >> Panels and check or uncheck the last four options for "Show Module Picker (F5)," "Show Filmstrip (F6)," "Show Left Modules Panel (F7)," or "Show Right Modules Panel (F8)" as desired. After you've done it this way a few times though, you will probably learn the keyboard shortcut equivalents for each. Press the F5 key and the Modules Picker will disappear. Press it again and it's back. The function key shortcuts for the others work the same way. Having one of these panels mysteriously disappear and not knowing how to get it back again is a problem experienced at some point by most new Lightroom users. Hit the wrong key on the keyboard in an application with this many keyboard shortcuts and there's no telling what might happen.
To hide both side panels, you can use Window >> Panels >> Toggle Side Panels, or simply hit the Tab key. Indeed, this is one of the easiest ways to accidentally lose your panels and be in a position where you need to find them again if you're a new user. There's also Window >> Panels >> Toggle All Panels, or its keyboard equivalent Shift-Tab to hide or show all four main panel groups.
Within the left and right modules panels are the controls for the various tools built into Lightroom. Even with that much space devoted to them, not everything will be visible unless you have a very large monitor. Window >> Panels will also give you access to hiding any or all of these including the Navigator, Histogram and other individual screen components. There are keyboard shortcuts for each but most aren't likely to be hit accidentally so I won't go into details here.
Each individual side group panel has a header where the title for that tool appears. If you click on the header of an open panel, that panel will be closed so that all that will show is the header with no actual controls beneath it. Click on the header again and the panel will expand back open. It's not necessary to click on the triangle icon to the right of the title to do this; you can click anywhere on the panel header. If you hold down the Control key (Command key on Mac OS) while clicking all the panels in that group will be closed or open as determined by the state of the one you click on. Control-click on one that's open and it will close along with everything else on that side of your screen.
If you right-click on the header for an individual tool panel you'll get a context menu giving you the ability to completely remove each of the panels in that group (left or right) if you don't or rarely need specific tools. Simply uncheck a module and it will vanish, header and all. To get it back again, just turn on the checkmark next to it on this same context menu. There's also "Show All" and "Hide All" to do the same thing for everything in that group all at once. Yes, "Hide All" will indeed leave you with a completely empty but still visible panel group. The Navigator on the left will remain as will the Histogram on the right since they are controlled separately but everything else will be gone. Right-click on the gaping blank space that remains and you'll thankfully still get the same menu so you get your panels back. At the bottom of the same menu are options for "Expand All" and "Collapse All" to let you keep the panel headers but collapse all of their contents.
On the outermost edge of both side panel groups you'll find a vertical strip with a small triangle icon. Click on this stripe with your mouse and the corresponding panel group will be hidden the same as if you had hit F7 or F8. If you hold down the Alt key (Option key on Mac OS) while clicking on this vertical stripe, you'll get a context menu with even more options. "Manual" is the way things start out. Panels only change visibility when you click on the vertical strip with the show/hide triangle icon. Selecting "Auto Hide" will hide the panel when you move your mouse away from it. "Auto Hide and Show" will do the same but will also cause the panel to automatically reappear when you move your mouse back over the show/hide control strip so you don't have to click on it. "Auto Hide and Show" appears to be the default option but in fact this is not the case. By default, showing and hiding the side panels is set to Manual yet the checkbox curiously shows in the wrong place until you have adjusted this yourself. There's also "Sync With Opposite Panel" which will cause Lightroom to use the same behavior to both left and right module group panels.
You can set the same automatic hide and show behavior with the top and bottom panels (the Module Picker and Filmstrip) using similar hide/show icon strips on the very top and bottom of the Lightroom application window.
You can also make the left and right panel groups wider or narrower by clicking on their inner edge (the divider closest to the main central image display area) with your mouse and dragging as needed. Combining options, you can drag the side panels as wide as needed but set them to auto hide so they get out of your way when you aren't using them.
It's also possible to temporarily get rid of the menu bar in Lightroom by switching to full screen mode via Window >> Screen Mode >> Full Screen. Together with the ability to hide the four main panel groups when not needed you can really get down to business and avoid clutter when working on an image. By pressing the "F" key by itself you can toggle full screen mode on and off. This is another way that new users sometimes inadvertently find themselves needing advice like what I'm covering here. As I said, press the wrong key in an application with this many keyboard shortcuts and there's no telling what might happen.
There's also a small toolbar strip directly below the main image area in the Develop module that can be gotten rid of either on purpose or accidentally by pressing the "T" key. Press it once and this toolbar will disappear. Press it again and it's back.
Another way to get rid of panel clutter in Lightroom is to use the "Lights Out" mode via the choices under Window >> Lights Out. You can dim everything other than the image you are working on, or blacken everything else out completely. The easiest way to cycle through these modes, and yet another keyboard accident waiting to get new users into trouble, is by pressing the "L" key on the keyboard. Press it once and the panels dim. Press it again and they go completely black. Press "L" one more time and things are back where you started as visible. Edit >> Preferences >> Interface gives you the ability to control just how dimmed "dim" is and what color Lights Out leaves you with. By default, the screen will go black but you can change it to other shades of gray or even white if you prefer. Sorry, no neon green.
There are even more ways to customize the Lightroom interface that I'll cover next week.
Go to Edit >> Preferences >> Interface. Not only can you change the shade of gray here that Lightroom will use as the fill color behind whatever is displayed in the main image area as well as the secondary display window, you can fill the area with a very fine pinstripe pattern. An odd touch to be sure, but I am unclear as to what use it actually serves. Indeed, if your monitor has a high enough resolution, the stripes that make up the pinstripe pattern are themselves barely perceptible with the result appearing nearly as just another shade of gray. Still, it's thoughtful of Adobe to provide a touch of class like this. 
Since you've just looked at a selection of end marks you might have been expecting the folder to filled with the files used to render what youv'e just seen but the built-in end marks live elsewhere. But if you put your own file here you can indeed use it as an additional end mark choice. 