"Can't open the boxes!?"
Position your cursor somewhere around the middle of the box, a red button icon appears. Double-click the button and the box will open. Same procedure to close the box.

"The boxes are empty!?"

The open box is a "bag" component of TTS. So there is no visual representation of what is inside. Try "dragging" stuff out of the box like you would out of a bag. Just place the hand cursor over the box, press left button down and "drag" by moving the hand out of the box while pressing left button. Drag to where you want and release mouse button to drop the item.

When starting the drag, be careful of not having the hand in the middle of the box, as it is reserved for the open/close button. So, if you see a red button icon over your hand, dont drag. Try moving the hand a little bit to the side until the button icon disappears.

Instead of dragging, you can also right-click the box and select "Search", which displays the contents of the box.