Can I make my GUI Buttons appear OVER a GUI Window?

I think the question is pretty self explanatory. I have two buttons that appear at the cursor position when something else is right clicked (I'm using the Brackey's inventory system, C# edition). So when I click on an item in the inventory, I want the buttons to show up. And they do, but they show up underneath the inventory. I can still click them and everything, but that's not exactly what I want. I want the buttons appearing over the GUI window that is the inventory. Here is the script I'm using to make my buttons appear, in case that's important:

 void OnGUI(){
         if (askQuestion == true){
 
             if (!mousePosHasBeenSet){
                 mousePos = Event.current.mousePosition;
                 mousePosHasBeenSet = true;
             }
             //Debug.Log ("askQuestion is " + askQuestion);
             //GUI.Box(new Rect(mousePos.x, mousePos.y, 25, 25), questionToAsk);
             //Debug.Log ("mouesPos y is " + mousePos.y);
             //Debug.Log ("The real y mousePosition is " + Input.mousePosition.y);
             if(GUI.Button(new Rect(mousePos.x, mousePos.y, 150, 20), yesString)){
                 selectedYes = true;
                 doDroppingOption ();
             }
             if(GUI.Button(new Rect(mousePos.x, mousePos.y + 20, 150, 20), noString)){
                 selectedYes = false;
                 doDroppingOption();
             }
         }
     }

And here is a picture showing what I'm talking about:

Super big thanks to anybody who offers help! All I need is to get those buttons to appear OVER the inventory window (which is a GUI.Window), rather than under.