Grid Inventory

[KodiakBehr]

I'm using the Grid Inventory Module as a starting point for a new game.

http://www.adventuregamestudio.co.uk/yabb/index.php?topic=28177.0

I wasn't bright enough to get it working from the module itself, so I tried adapting the demo instead in order to understand how it works through ablation.

In the demo, there are two inventory grids.  I only need the one, so I started by trimming all references to gInventory2 and DeathInv, while preserving the if-statement logic.  When I do that, line 386 on Module0 crashes the game.

Code: ags

InventoryItem* GridInventory::GetAtScreenXY(int x, int y) {
  GUI *pg = this.pInvWin.OwningGUI;
  int X = this.pInvWin.X + pg.X;
  int Y = this.pInvWin.X + pg.Y;
  
  String id;
  
  if (pg.Visible && this.pInvWin.Visible && this.pInvWin.Enabled && this.pInvWin.Clickable) {
		if (x >= X && x < X + this.pInvWin.Width && y >= Y && y < Y + this.pInvWin.Height) {
		  
		  int pos = (x - X) / this.pInvWin.ItemWidth + ((y - Y) / this.pInvWin.ItemHeight) * this.pInvWin.ItemsPerRow;
		  
		  id = this.itemId.Substring(pos * 3, 3);
		  		  
		  if (id.AsInt)
				return inventory[id.AsInt];
		}
	}
	
	return null;	
}

Can't for the life of me figure out what that section does.  I'm probably in over my head.

Does anybody have experience with this module, or any other grid-inventory module, that can offer guidance towards its clean implementation?

[KodiakBehr]

Disregard.  Frankly, grid-inventory adds too much complexity to my game without adding a lot of value. 
I'm going to take some advice from the critics of my last game and keep the interface clean and simple.