Bootstrap 模式问题 - 滚动被禁用

Question

新手上路，请多包涵

我有一个模态，在该模态中，有一个下拉菜单显示大量隐藏内容，它正在工作。

现在，当您打开下一个模态，堆叠在第一个模态之上并将其关闭时，下方模态上的滚动将被禁用。

我创建了一个完整示例，包括复制我面临的问题的步骤。你可以在这里看到它。

 <!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <link href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" rel="stylesheet">
    <title></title>
    <style>

    </style>
</head>
<body>

    <input type="button" data-toggle="modal" data-target="#modal_1" class="btn btn-lg btn-primary" value="Open Modal 1" >

    <div class="modal fade" id="modal_1">
        <div class="modal-dialog modal-sm">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
                    <h4 class="modal-title">First Modal</h4>
                </div>
                <div class="modal-body">

                    <form class="form">

                        <div class="form-group">
                            <label>1) Open This First: </label>
                            <input type="button" data-toggle="modal" data-target="#modal_2" class="btn btn-primary" value="Open Modal 2" >
                        </div>

                        <div class="form-group">
                            <label>2) Change this once you have opened the modal above.</label>
                            <select id="change" class="form-control">
                                <option value="small">Show Small Content</option>
                                <option value="large">Show Large Content</option>
                            </select>
                        </div>

                        <div id="large" class='content-div'>
                            <label>Large Textarea Content.. Try and scroll to the bottom..</label>
                            <textarea rows="30" class="form-control"></textarea>

                        </div>

                        <div id="small" class='content-div'>
                            <label> Example Text Box</label>
                            <input type="text" class="form-control">
                        </div>

                    </form>
                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                </div>
            </div>
        </div>
    </div>

    <div class="modal fade" id="modal_2">
        <div class="modal-dialog modal-sm">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
                    <h4 class="modal-title">Second Modal</h4>
                </div>
                <div class="modal-body">

                    <hp>This is the stacked modal.. Close this modal, then chenge the dropdown menu, you cannot scroll... </h5>

                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                </div>
            </div>
        </div>
    </div>

</body>
<script src="http://code.jquery.com/jquery-1.11.0.min.js" type="text/javascript"></script>
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js" type="text/javascript"></script>
<script>

    $(document).ready(function() {

        $(".content-div").hide();
        $("#change").change(function() {
            $(".content-div").hide();
            $("#" + $(this).val()).show();
        });

    });

</script>
</html>

这里有一个 Bootply 来展示实际的行为：

靴子