function _onClickBtnEditLabel(evt){
            var target = $(evt.currentTarget);

            elements.editLabelForm.data(target.data());
            elements.editLabelName.val(target.data("labelName"));
            elements.editLabelColor.val(target.data("labelColor"));
            elements.editLabelCategory.data("select2").val(target.data("categoryId"));
            elements.editLabelForm.modal("show");

            _updateInputBySelectedColor(elements.editLabelName,
                                        elements.editLabelColor,
                                        target.data("labelColor"));
        }
"click" event handler of edit label button.
Shows modal dialog element.editLabelForm with .data() of clicked button.

@param evt
@private