duck

static var clickMaster : Clickable

function ClickMaster() : Clickable
{
    if (clickMaster == null)
    {
        clickMaster = this;
    }
    return clickMaster;
}

function PixelClick(type : String)
{
    do the raycast,
    check if a 'clickable' compnent is attached to the collider's GO
    if so, sendmessage "type" to the clickable's root gameobject
}

function Update() {
    if (ClickMaster() == this)
    {
        // I am the master of clicks!

        if (Input.GetMouseButtonDown(0)) { PixelClick("LeftMouseDown"); }
        if (Input.GetMouseButtonUp(0)) { PixelClick("LeftMouseUp"); }
        if (Input.GetMouseButtonDown(1)) { PixelClick("RightMouseDown"); }
        if (Input.GetMouseButtonUp(1)) { PixelClick("RightMouseDown"); }

    }
}