Lime.Inventory

Check out version 2!

This is flexible inventory system for Game Maker Studio 2.3.7+. You can create many inventories with one function! Drag and drop windows and items. You can setting up it like you want: change colors of inventory or set background and slot sprites, and also has the support of nine slice sprite.

Documentation 

GitHub

Features:

* Easy to setup.
* Easy to use functions.
* Many settings.
* Drag and drop windows.
* Very fast. Surfaces are used and updated only if it is really needed.
* Full commented and organized code.

Apocalypse style inventory example:

//CREATE EVENT
inventory = InvCreate(6,3);
InvSetName(inventory, "Apocalypse style");
InvSetBackSprite(inventory, sStalkerInvBack);
InvSetMainSlotSprite(inventory, sStalkerInvSlot);
InvSetCursorSprite(inventory, sStalkerCursor);
InvSetIndentOfCell(inventory, 10);
InvSetBordersSize(inventory, 10, 10, 63, 10, 10);
InvSetPosition(inventory, room_width div 2 - inventory.inv_surf_w div 2, inventory.invPosY - 16);
InvToggleAnim(inventory, true);
//Add random Items
for (var i = 0; i < inventory.inv_slots; ++i) {
    var _item = ITEM.knife + irandom(ITEM.item_number-ITEM.knife-1);
    InvSetSlotItem(inventory, i, _item, 1 + irandom(GetProp(_item, ALL_PROPS.maxstack)-1));
}
//PRESS "E" BUTTON EVENT
InvToggleAnim(inventory);

If you have some problems or suggestions or found a bug, please contact with me!

For help, go to my Discord server in the appropriate section
https://discord.gg/zaSvSDjPpG