The “Edit Map” tab lets you add different objects to your map (icons, lines, text, etc….). It also provides features that show or hide a grid on your map, letting you easily align your objects, or lock/unlock all your map configuration for quick access to the properties of the different objects.
When you want to make a change to your map, it is always a good idea to “Unlock” all of the map, in this way you can work on the whole map and without having to remember if an object is locked or not. Remember that to work on a map, the map should be unlocked, and to work on an object, the object should be unlocked. You can avoid complicating your life by unlocking everything before working on the map.
The show/hide feature can be useful when you have many objects and images to position on your map and want everything to be correctly aligned.