Support for defining active panes, allowing players to freely drop items from their inventory

[killertuling]

pane design concept is great, One of the best API I've ever used in a Spigot plugin.

but in high versions of Minecraft, more and more people use title to customize the GUI's background, and rarely use items to impl.
Imagine that I now have a need:
Allows a pane or slot to be defined as an “active pane”, player can fetch or place item from it, then change other pane or title according it. but now, I have to use update() , but it will be reset...

I think IF you can create a new kind of pane, it's called active pane;

1. It should help us solve problems such as how players can interact more naturally with the active pane, such as when using shift+leftclick, swap item with cursor...
2. Also, it will not be reset by the update method
3. it can choose item will drop, delete, or return to Inventory ,when closing the gui
4. when it change, can trigger some events;
   
   it some of my suggestions for IF's features
   I think the only shortcoming of IF is not support for active slots, and IF splits the gui into panes, but you can't select some panes to not update
   My english is not good,sorry