static/ext/src/ux/form/field/ClearButton.js
function(event, htmlElement, object) {
            if (!this.isLeftButton(event)) {
                return;
            }
            // 2011-11-30 Ing. Leonardo D'Onofrio leonardo_donofrio at hotmail.com
			if (this.textField.clearValue) {
				this.textField.clearValue();
            } else {
				this.textField.setValue('');
            }
            // end Ing. Leonardo D'Onofrio
			this.textField.focus();
        }
function(event, htmlElement, object) {
            if (!this.isLeftButton(event)) {
                return;
            }
            // 2011-11-30 Ing. Leonardo D'Onofrio leonardo_donofrio at hotmail.com
			if (this.textField.clearValue) {
				this.textField.clearValue();
            } else {
				this.textField.setValue('');
            }
            // end Ing. Leonardo D'Onofrio
			this.textField.focus();
        }
///////////////////////////////////////////////////////////////////////////////////////////////////  Mouse event handlers  /////////////////////////////////////////////////////////////////////////////////////////////////// 
Tada - the real action: If user left clicked on the clear button, then empty the field