function positionHue(event)
    {
        var hsva = this._hsv.slice();
        hsva[0] = Number.constrain(1 - (event.x - this._hueAlphaLeft) / this._hueAlphaWidth, 0, 1);
        this._innerSetColor(hsva,  "", undefined, WebInspector.Spectrum._ChangeSource.Other);
    }
@param {!Event} event
@this {WebInspector.Spectrum}