I was wondering if I can make more sections in one inventory GUI, between which it would be possible to move objects and one of theese sections would be accesable from another inventory GUI. (This would be what the character's got in his pockets and therefore can get while he's in a sword fight)
You could use a different character for each 'section' of the Inventory. You'd have to have a couple of InvWindow objects on your GUI, each with a different 'Character ID' property (same as the InvWindow.CharacterToUse property (http://www.adventuregamestudio.co.uk/manual/InvWindow.CharacterToUse.htm) in script). Moving items between the sections will then be a case of taking it way from one Character, and giving it to another.
It's not really possible to do it using a single Character's inventory, AFAIK.