Unable to select text in Kendo Sortable with handle

I have a set of sortable widgets very similar to the demo . JS here:

    var column1Sortable = $(column1Selector).kendoSortable({
        filter: ".panel",
        cursor: "move",
        handler: ".panel-header",
        connectWith: column2Selector,
        change: sortableOnChange,
        placeholder: sortablePlaceholder,
        hint: sortableHint
    }).data("kendoSortable");
    var column2Sortable = $(column2Selector).kendoSortable({
        filter: ".panel",
        cursor: "move",
        handler: ".panel-header",
        connectWith: column1Selector,
        change: sortableOnChange,
        placeholder: sortablePlaceholder,
        hint: sortableHint
    }).data("kendoSortable");

      

        
        
        
      

    

The HTML for the panels looks something like this:

<div class="panel">
    <div class="panel-header">Header</div>
    <div class="panel-content">
        ... selectable text here ...
    </div>
</div>

      

        
        
        
      

    

While I was setting the parameter handler

to the div .panel-header

, I cannot select any text in the area .panel-content

. The mouse cursor shows the text cursor, but nothing is highlighted when trying to select.