I call it from onKeyPressed() event. Now i can see my GUI and items, but I can't edit it. Items just go back in their slots when I try to take them. Is it GUI problem or I need to fully setup my messages and message handlers first? I have class GUICustomPlayerInventory extends GuiContainer and separate inventory stored in extendedProperties of player. I want to fully replace standart player inventory with mine. What's simplier: to overriding player.inventory or using my current method?