Example: Create a GUI

Create a PlayerHider for the Hub

For the hotbar

When the player joins only the following code is needed to give the players a button in the hotbar.

HotbarGui hotbar = Gui.hotbar();
hotbar.setDefaultClickHandler(c -> c.cancel()); // Cancel all hotbar events
hotbar.addModifier(Modifiers.fillEmpty(new ItemStack(Material.STAINED_GLASS_PANE))); // Fill all empty slots with stained glass
IWidget playerHider = new Button(this::openSelector) // Run on click
        .setMaterial(Material.BLAZE_ROD) // Blaze rod as button
    	.setTitle("§ePlayerHider") // Title
		.setSlot(4); // In the middle of the hotbar
hotbar.addWidget(playerHider); // Add the widget to the hotbar
hotbar.open(player); // Change the hotbar for the player

The GUI

For the UI we will use an brewing stand. This is our openSelector function:

public void openSelector(ClickContext e) {

Let us first create the inventory of type BREWING:

	InventoryGui gui = Gui.inventory() // Create an inventory UI
			.setGUITitle("§ePlayerHider")
			.setInventoryType(InventoryType.BREWING); // Set the type

Add the options for player hider:

    // Create three buttons for the player options
	IWidget hidePlayers = new Button(this::hideAllPlayers)
            .setMaterial(Material.GLASS)
			.setTitle("§cHide all players").setSlot(0);

	IWidget showPlayers = new Button(this::showEveryOne)
            .setMaterial(Material.SEA_LANTERN)
			.setTitle("§aShow all players").setSlot(1);

	IWidget showTeam = new Button(this::showTeamOnly)
            .setMaterial(Material.GLOWSTONE)
			.setTitle("§5Show only teammembers").setSlot(2);
    
    // Add the buttons to the UI
	gui.addWidget(hidePlayers);
	gui.addWidget(showPlayers);
	gui.addWidget(showTeam);

For some finishing touches add a descriptive item:

    // Add a description item in the top that does nothing
	gui.addWidget(new BasicButton((f) -> {})
          .setDisplayItem(new ItemStackBuilder(Material.PAPER, 1, "§7» §ePlayerHider §7«")
			.setLore(Arrays.asList("",
					"§8§m--------------------",
					"§eKlick on the items to",
					"§ehide certain players",
					"§8§m--------------------",
					""))
			.build())
         .setSlot(3));

Now show the ui to the player:

	gui.open(e.getPlayer());
}

As you can see: You are able to create a powerful GUI in just under 30 Lines of code hassle free.