GUI.Button to display multiple Rows and Columns

Hello again,
i am having problem with drawing those GUIButtons. So far i can create a GUIWindow with one row made of 15 buttons. I am thinking more about 5 rows and 15 columns.

public var buttonWidth				:	float = 40;
public var buttonHeight				:	float = 40;

private var _inventoryRows			:   int	  = 5;
private var _inventoryCols			:   int   = 15;	


function someWindow(_WindowID) {								
	var texToUse : Texture;
	var y : int = 0;
	var x : int = 0;
		
		for(; y < _inventoryRows; y++) {
			
			for(; x < _inventoryCols; x++) { 
				
				GUI.Button( Rect(10 + (x * buttonWidth),  120 + (y * buttonHeight),

`` buttonWidth, buttonHeight), x + y * _inventoryCols.ToString());

			}
				
		}	
	GUI.DragWindow();
}

Could you help me please, and thank you

ok i will try that