Multiworld GUIs
World Downloader has two multiworld GUIs, one of which is displayed the first time you are on a server and the other one each time you start downloading or open the options on a multiworld server.
The Multiworld support GUI is used to select whether multiworld support is enabled or disabled when you first join a server. You can only make the choice once*, so chose carefully!
This GUI is pretty simple: Click the button in the middle to toggle whether you want multiworld support on or off, and then select "Done" to submit.
You can also select "Cancel" if you don't know whether you want to enable multiworld yet - relatively simple. Selecting cancel postpones the decision completely; you can't start download without choosing.
*The decision can be changed by renaming the server in the main Minecraft multiplayer GUI, or by deleting the WorldDownloader.txt file in the world's folder. Or, you can delete the world folder completely.
Note: This GUI looks different in the current public build. In that version, selecting a world will immediately chose it, and there is no search.
The multiworld select GUI is used to identify which world you are on when on a multiworld server. It is displayed whenever you start downloading or open the World Downloader options menu. To learn why this GUI is needed, see Multiworld.
When you first open the multiworld select GUI, there will be a row of disabled buttons at the bottom. Select "New name", and enter the name of the current sub-world. You can create sub-world for each sub-world on the server before you have started downloading in them, or you can wait until you are in that world to do so.
Note: You don't need to put the dimension for the world in the name. However, if you do, you will have separate world files for each dimension, which is beneficial if you want to spawn in either dimension. But if you want to directly use nether portals to connect between each world, use the same world for all dimensions. See Multiworld for more information.
Once you've created a new world, select the world you want by clicking on its button. This will highlight the world (and in the future, some additional information about the world will be displayed). When you have the world you want, select "Use selected world".
If you have more worlds than fits on a single row, you can use the < and > buttons to scroll within the list. You can also use the search box to help narrow down the possible worlds.
Selecting cancel will, of course, cancel world selection (and any download that you would be starting). However, it will not undo any new subworld names you created.