How to disable the third zoom button in webview of Android ?

Question

I want to disable the third button that creates a rectangle to zoom in other than +/- buttons in my WebView which uses builtin zoom controls. How can I do that ? I am able to do this for WebView without using built-in zoom controls by

myWebview.getZoomControls().getTouchables().get(2).setVisibility(View.INVISIBLE);

But how to do the same for built-in zoom controls ?

Also I am extending the WebView class and overriding the onTouchEvent for tracking touch events inside my WebView as this is not possible by default, since zoom buttons consumes the touch event.