How to use a filter to make a shader distort the scene behind it

The water processor and filters works perfectly, what makes an unwanted effect is the refraction effects on the ShaderBlow project. The “filter” one (the one that use a filter instead of a sceneprocessor) uses the same “pattern” as here.
In that topic there is a heat haze example that have the same issue, it distorts any object that cross “the line” between the camera and the distorting object, what is not realistic at all.