Prevent mouse click through GUI Texture?!?!

Hi Guys, I appriciate any help you can offer, I have looked around but cant seem to find a proper solution to this problem. I have GUI textures in my scene, and pressing them activate scripts. On being a "Buildmode" which places cube objects in my scene. Single clicking the gui texture to activate this mode works, but the mouse click also goes through the GUI texture and places a cube object in my scene. Here is my code:

function Update () { if(Input.GetMouseButtonDown(0)) { if(tex.HitTest(Input.mousePosition)) { if(mode.buildmode == false) { tex.texture = ontex; mode.buildmode =true; } else { tex.texture = offtex; mode.buildmode = false; } }

} }

I need build mode to be enabled but prevent the button being clicked through.

Thanks in advance for any help you can provide, James.