Tooltips - when you hover the mouse over an item it will show you the details
Icons - each item is represented by a unique icon. This icon is displayed on the Inventory screen
Drag and Drop - You can click an item and drag it to another 'slot'. The item's icon follows the mouse as you hold down the button and when you let go, the item is moved to that slot. If the inventory slot is not empty, the items are swapped.
The number of Inventory and Heatsink slots change depending on the chassis you have installed. Bigger chassis mean more inventory space and more heatsink space.
It's still untidy because i'm using scratch graphics but the inventory background and the tooltips backgrounds are bitmaps so they can be redrawn at a later date with nice fonts, borders etc. I'm also displaying a bitmap of the chassis in the centre of the screen. I will add some animations and stuff later to make it a bit nicer to look at. I'm hoping it will look a bit like the inventory screen from this mech game I googled. Not exactly the same but the same style.
UI work is so boring!