Create kendoUpload:

var ku = $('#file').kendoUpload({});


Destroy it:
$('#file').data('kendoUpload').destroy();

Create again with files option:
var ku = $('#file').kendoUpload({
     files: [{name: 'name', size: '5000', extension: '.jpg'}]
});

and try to remove file by click on cross, you'll get exception:

Uncaught TypeError: Cannot call method 'remove' of undefined kendo.web.js:47077

Given a object such as Person which has an optional child object such as IdentityDetails (1:0/1) I cant get this to work properly. I just dont want to show the template if identitysection is null. 

Even when hasIdentitySection returns false this produces an exception because it tries to evaluate identitySection which is null

<div data-bind="visible: hasIdentitySection">           
 <div data-bind="source: identitySection" data-template="identity-template"></div> </div> 

There is interface inconsistency in some examples/demos using form-like ListViews. It can cause other developers use it as-is and get UX issues. Please check:
http://demos.kendoui.com/mobile/application/transitions.html#view-transitions-login
http://demos.kendoui.com/mobile/forms/index.html#/

If you click/tap between text label and center of list item (where input starts) nothing will happen. And that's wrong behaviour at least for iOS interfaces. Input editing should be activated on click/tap in any place of list item.

Fortunately, it can be easily fixed by adding display: inline-block and width: 100% to <label>

I need homogenous data items for multilevels in your tree control.
Most data structures coming from our services are not homogenous.
We use the following to create a homogenous structure for the tree.
Maybe you could incorporate something like this - note that we use angular, and I use their $parse service in my implementation:

// CALLER:

          var levelDescriptors = [
            { item: "functionGroup", items: "functions" },
            { item: "this", items: null }];
          itemHierarchy = Portal.buildItemHierarchy(
            functionGroups,
            levelDescriptors,
            $parse);

// UTIL CODE:

    buildItemHierarchy: function(hierarchicalItems, levelDescriptors, $parse) {
      var hierarchicalDataItems = [];
      if(Portal.isDefined(hierarchicalItems)) {
        hierarchicalDataItems = Portal.createHierarchicalDataItems(0, hierarchicalItems, levelDescriptors, $parse);
      }
      return hierarchicalDataItems;
    },

    createHierarchicalDataItems: function(level, levelItems, levelDescriptors, $parse) {
      var levelDataItems = [];
      if(Portal.isDefined(levelItems)) {
        if(Portal.isDefined(levelDescriptors)) {
          if(level < levelDescriptors.length) {
            for(var i=0; i<levelItems.length; i++) {
              // extract datasource for current level.
              // create an associated node data item.
              var levelItem = levelItems[i];
              var levelDescriptor = levelDescriptors[level];
              var item = levelItem;
              if(levelDescriptor.item !== "this") {
                item = $parse(levelDescriptor.item)(levelItem);
              }
              if(Portal.isDefined(item)) {
                var levelDataItem = Portal.createNodeDataItem(item);
                levelDataItems.push(levelDataItem);
                // extract children for current level.
                // create associated (child) node data items.
                var items = $parse(levelDescriptor.items)(levelItem);
                if(Portal.isDefined(items)) {
                  var itemsLevel = level + 1;
                  levelDataItem.items = Portal.createHierarchicalDataItems(
                    itemsLevel,
                    items,
                    levelDescriptors,
                    $parse);
                }
              }
            }
          }
        }
      }
      return levelDataItems;
    },

    createNodeDataItem: function(item) {
      return {
        id: item.id,
        text: item.name,
        dataSource: item,
        expanded: false,
        items: []
      };
    },

This bug is visible in your demo at http://demos.kendoui.com/web/grid/editing.html.

in Grid / Batch editing when you enter a decimal value in column Units in Stock, then click "Save changes"
page does not save the value and the page does not do any saving.

perhaps there is a bug in NumericTextBox which exists in function caret(element, position)
We get an unspecified error for this bug in our project 

Kendo UI for mobile looks really promising. However, when I tried your demo app on Safari Mobile on iOS, it seems that in the index, when I tap on a menu item, the first tap is almost never catched.

It usually takes two taps for a menu item to catch the click event and load the demo. I am on iOS (6.1.3) and on Safari. A few friends of mine also noticed this problem on Android phones. Are we the only ones to notice this behavior ?

Actually the forms are created in a list. The label and the control elements are positioned side by side. For some cases it would be helpful to position the label above of the control element (see also WP8).

kendoui.all.js and kendoui.all.min.js are not from the same codebase. The bug appear to be in datawiz when trying to load data from the remote location and ammend it via dataFilter.
Minified version in my case works while the source populates the grid with undefined value. No error shown in console.

Kendo Grid Select Method is working good if you have only one grid on a page, but if you have more than one grid on the page then its not working properly.
To check this issue please check the following code snippet 

http://jsfiddle.net/amolkhot/AZz8z/1/

I also found solution for that, in select method of grid I saw that you guys are doing items=$(items) [Code Line # 25089 in kendo.all.js]
it has to be items = $(that.element).find(items)

I hope this change will be done in next release build.

Thanks,
Amol Khot

Happens In chrome (and opera) when a grid is first rendered.
If you click the sort or filter icon, the grid becomes focused.  As a result, the browser scrolls the window, even though the grid is already focused.  This causes an issue if you have a fixed header, since the grid becomes obstructed.  The following is a modified version of existing kendo code, and will keep the grid where it belongs, so it does not move (works for us).  Hope it helps, and either way thanks for a great product:

   function focusTable(table, direct) {

     // MODIFICATION:
     // capture window x/y position in order to restore it at end of function.
     // this is necessary since chrome/opera will scroll focused elements into
     // view, even if they are visible.

     var x = window.x;
     var y = window.y;
     var scrollable = $(table).closest(":scrollable('vertical')");
     var scrollLeft= scrollable[0].scrollLeft;
     var scrollTop = scrollable[0].scrollTop;

     var msie = browser.msie;
     if (direct === true) {
         table = $(table);
         var condition = msie && table.parent().is(".k-grid-content,.k-grid-header-wrap"),
             scrollTop, scrollLeft;
             if (condition) {
                 scrollTop = table.parent().scrollTop();
                 scrollLeft = table.parent().scrollLeft();
             }

             if (msie) {
                 try {
                     //The setActive method does not cause the document to scroll to the active object in the current page
                     table[0].setActive();
                 } catch(e) {
                     table[0].focus();
                 }
             } else {
                 table[0].focus(); //because preventDefault bellow, IE cannot focus the table alternative is unselectable=on
             }

             if (condition) {
                 table.parent().scrollTop(scrollTop);
                 table.parent().scrollLeft(scrollLeft);
             }

     } else {
         $(table).one("focusin", function(e) { e.preventDefault(); }).focus();
     }

     if(browser.webkit || browser.opera) {
       window.scrollTo(x, y);
       scrollable.scrollTop(scrollTop);
       scrollable.scrollLeft(scrollLeft);
     }
  }
  
  function tableClick(e) {
    var currentTarget = $(e.currentTarget),
        isHeader = currentTarget.is("th"),
        currentTable = currentTarget.closest("table")[0];

    if (kendo.support.touch) {
        return;
    }

    if (currentTable !== this.table[0] && currentTable !== this.thead.parent()[0]) {
        return;
    }

    this.current(currentTarget);

    // MODIFICATION:
    // Removed timeout so the table can focus now (as required).
    // That way if the user clicks the filter icon first, the table
    // will focus and the filter menu will display.  Else table will
    // focus some 250 msecs from now, after the filter menu shows.
    // In such a case, the menu would blur immediately, and close.

    if (isHeader || !$(e.target).is(":button,a,:input,a>.k-icon,textarea,span.k-icon,.k-input,.k-multiselect-wrap")) {
        focusTable(currentTable, true);
    }

    if (isHeader) {
        e.preventDefault(); //if any problem occurs, call preventDefault only for the clicked header links
    }
  }

   ui.plugin(Grid);
   ui.plugin(VirtualScrollable);
})(window.kendo.jQuery);

The new chart select feature is great but it only works with vertically oriented charts (column), but I need it for stacked bar charts. I'd also like to be able to disable the grab handles and programatically specify the range. I have multiple similar charts, a category-specific grid with additional info, and a dropdownlist for selecting the category. You can also select the category by clicking any of the chart elements.

There is no pure HTML5+JS equivalent for RadSpell available anywhere that I can find. We currently use RadSpell but are trying to move away from WebForms. RadSpell is holding us back.

Would like to have a splitter in mobile controls.

line 26486 
has this:
data = extend({}, { field: group.field, value: group.value }, group.aggregates[group.field]),
should be this:
data = extend({}, { field: group.field, value: (typeof(group.value) === 'undefined' ? null : group.value) }, group.aggregates[group.field]),
Or something like that.  In any case, without that change, the following will blow up when cell value is undefined.
groupHeaderTemplate: "#=value#"

accordion widget is missing. please add it

Chrome displays a vertical scrollbar for all kendo window using iframe. Example:
http://jsfiddle.net/Vz2Z4/

Currently if you drag weekly event from Tuesday to Wednesday for example and change to edit series it is not being changed to Wednesday. It stays on Tuesday. I think most of people would expect it to be rescheduled for Wednesday.

kendo will be more beautiful if kendo add a scrollbar plugin, and use it in some other widgets(DropDownList, MultiSelect, and so on); and I find something that I think it's not pretty: the grid widgets in metro theme, when I click the head of the grid, the order icon is not display immediately.

Is there some way to flash(refresh) one of the nodes in the "TreeView" widgets?

And how can I change the attr of the node easily?

Grid drop down does bind when its data contains '

when drop down bind to item that contains ' it does not work