Thanks for the info. With the second question I meant connecting an action to an panel, but I quess that's only possible with entities.
When I began to try making the inventory I used panels with buttons for the inventory and entities (/sprites) for the items. All went well except for the fact that I forgot that entities move with x, y and z coordinates and not with only x and y (like panels) and that panels are in frond of entities. Than I tried to make an inventory entirely made of entities (I was getting a bit tired of panels :P) but that didn't work either for me (hard with the x, y and z coordinates and such). I noticed that both entities and panels have their advantages and disadvantages for creating an inventory; entities can have an action connected to them and can have skills which really makes it alot easier but else they make it more difficult.

Speaking of skills, I saw in the manual that panels have skill_x and skill_y, what do do they do exactly?

I also found that rpgtemplate by Claus N., Nighthawk Arts has a good working inventory in it (similar to the deus ex and diablo ones), I'm going to try that one out.

Again thanks for the helpfull comment!