私は自分の問題の解決策を見つけました
<div id="documentPageDraggableHelper" class="gallery ui-helper-reset"></div>
ページを構成する他のdivの外側に追加しました:
<div id="mainCategorizerContainer">
<div id="documentPageRecords" class="documentPagesRecordsArea ui-widget-header">
<span></span>
</div>
<div id="uncategorizedArea" class="uncategorized-area" >
<div class="uncategorized-document-pages-list-area">
<div id="scroll-content-uncategorizedPagesList" >
<ul id="uncategorizedPagesList" class="gallery ui-helper-reset ui-widget ui-helper-clearfix uncategorizedPages">
</ul>
</div>
</div>
</div>
<div id="categorizedArea" class="categorized-area">
<div class="document-category-list-area">
<div id="scroll-content-documentCategoryList" >
<ul id="documentCategoryList" class="ui-helper-reset">
</ul>
</div>
</div>
<div class="categorized-document-pages-list-area">
<div id="scroll-content-categorizedDocumentPagesList">
<ul id="categorizedDocumentPagesList" class="ui-helper-reset" >
</ul>
</div>
</div>
</div>
<div id="splitDocumentDialog"><span id="splitDocumentDialogContent"></span></div>
<div id="documentPageDraggableHelper" class="gallery ui-helper-reset"></div>
</div>
左側のドラッグ可能なリストに、次のようなappendToオプションを追加しました
uncategorizedPagesListDraggableOptions = {
cancel: "a.ui-icon",
revert: "invalid",
containment: "document",
helper: "clone",
cursor: "move",
appendTo: '#documentPageDraggableHelper'
}