In the Palette Pditor you can edit palettes, create new palettes, import palettes, merge and delete palettes. You also have a option to refresh palettes. You have to use this option to make palettes installed after you started Gimp available and ready for use.
Either you can choose the palette to edit in the palette select dialog or you activate it in the palette editor with a single left clicking on it. The palette that you are about to edit will now appear in the edit area. If the palette has a large amount of colors then each color cell in the palette can be rather small. To be able to view and edit the palette you can therefore zoom in and out with the zoom buttons.
To change the name of a color cell you first mark it by left clicking on it. The Name field next to the zoom buttons will be activated and you can change the name.
The edit menu will appear if you right click in the edit frame. Choose to edit and the standard Gimp Color selector will appear and you will be able to change to color in the color cell that you right-clicked in. New will add a color at the end of the palette. The new color cell will inherit the color of the cell that you brought up the menu in. To alter the newly created cell you have to right-click in it and choose edit. Delete in the right click pop up menu will delete the color cell from which you brought up the menu in (you will not get a confirmation window).
Will create a new empty palette in the edit frame, a confirmation window with where you name the new palette will appear. When you have created your new palette, you have to insert color cells. You do that by right-clicking anywhere in the edit area and choose new from the popup menu.
Will delete your palette.
Will bring up the Import dialog where you can create a new platte from a gradient, image or indexed palette.
You are able to merge palettes in the editor, the new palette is a combination of the selected palettes. To merge two or several palettes you have to mark the palettes that you want to merge and click on Merge which will bring up the Name dialog. There are two ways to mark palettes either you <Modkey> click, you will then mark a single palette each time (or unmark). You can also <Modkey> click which will mark all palettes from the first marked to the last marked palette.