2.0.X | Customization Helper
Maybe you've already discovered the weird menu bar in all your Minecraft GUIs.
This is the Customization Helper. It contains everything you need to customize your menus.
Most of the tabs in this bar are focussing on the current menu you see.
You can create layouts for the current menu there, get informations about the menu and more, but the Customization Helper also contains some stuff that's not related to the current menu, like creating and managing custom GUIs.
The Reload Button
The little curved/spinning arrow button on the right side is the reload button.
It does not apply changes made to animations.
You need to restart your game after changing or creating animations.
The first option in this tab toggles the customization system for the current menu (not for all menus).
By default, the customization system is disabled for all menus and will not show any layouts and customizations you apply to a menu.
To change this, simply switch this option to On by leftclicking it.
This option allows you to create and manage layouts for the current menu.
With layouts, you can completely customize the look and feel of menus.
The last option in this tab contains things for advanced users.
You can override the current menu with one of your custom GUIs here.
Managing Custom GUIs
The Custom GUIs tab contains everything you need to create and manage your custom GUIs.
Well, there's not really much to say about this tab.
You can open custom GUIs with custom buttons. This is the recommended way to use them.
Please be careful when overriding a menu with a custom GUI. This should only be done when you really can't edit the menu using a layout.
Get Informations about Menus
The Tools tab contains useful tools to get informations about the current menu.
NOTE: You can leftclick the menu identifier to copy it to your clipboard.
This one, when activated by clicking on it, will show you informations about a vanilla button, when you hover over it. (Doesn't work for custom buttons)
It's basically a debug tools to check things like the button size and positon without needing to open the Layout Editor.
Other Useful Stuff
The Miscellaneous tab contains everything that doesn't really fit in a category. For now, you can force-close menus with it and open "dead" instances of some menus that you normally can't customize, because they disappear to fast, like the world loading screen.
NOTE: This tab maybe looks different for you, because it doesn't have the same content in all MC versions.