Add support for the HTML 5 data-* so we can access the Kendo API in this elegant and unobtrusive way.

Example, Kendo's date picker could be called this way something like this:

<input type="text" class="myClass" data-kendo-date="true" data-format="dd/MM/yyy" data-min-date="13/12/2013" />

Currently complex elements (Like the Grid and the Chart) have so many properties and methods that the page has so many DOM elements it takes forever to load.

It would be awesome if you added masking to input fields, similar to what you've done with validation. Many times I need to add formatting to the display of a field that and I don't want to store the extra characters associated with the on screen formatting. Formatting for telephone numbers, email addresses, currency are the ones immediately useful. Although other libraries exist for these, it would be nice to consolidate them into a single library!

Although Kendo has fency filters with different operators (StartsWith, Contains) on different columns based on data type, Most business users  like to have excel AutoFilter(Multi select checkbox) where they can choose what companies, countries they want to see

You can see a live demo here at - select company, country or any other column.
http://demos.devexpress.com/MVC/GridView/Filtering

I had a combo and grid on page.
Combo has two values: value 1 with 372 items and value 2 with 21 items.
grid has paging enabled with pagesize 20 and serveroperation false.

Now when i select value 1 in combo then all 372 items are displayed in grid and then i go to 6th page of grids paging at this time in grids paging it is shown "101 - 120 items of 372 items"and then if i select value 2 in combo then no items are displayed in grid but paging shows "101 - 21 of 21 items" because it is yet on page 6 but this time there is no page 6 and in controller the request shows page 1. This is a bug.

Regards,

It would be very beneficial to have the ability to set our own labels on our chart types. This way instead of having labels set a set amount for example 10s, for 1 to 100, labels could be set at just the intervals that make sense for our chart. Like 1,15,63,100. Since ranges can already be set at a variable amount it would be helpful to label those at the point they change.

Allow charts to define multiple chart areas.  

This would be particularly useful in scenarios where historical data for an industrial process must be visualized in line charts (e.g. temperatures, pressures, valve positions, flow rates etc.)

Split buttons would allow to have a menu item that target a specific page and at the same time have sub items. It is possible to do it with the current version however it only works with mouse devices, the split button would provide the same functionality for touch devices.

It would be cool if it were at least easier to put a kendo style modal within a kendo window that covers the content of the window. 
An example: Confirmation of action, if a user clicks to close the window it would be nice if a modal could be displayed, covering only the window content until the user confirms or cancels.

Please add a click event to the Chart Legend similar to the seriesClick event that currently exists.

I know you have special tag structure so that you can implement certain features.  However, for UI elements like the drop-down, numeric input and date-picker, it would be really great to use (or have an alternative control to us) native html elements and data- attributes that are easily recognized by mobile devices and newer, desktop browsers.  For example, for the drop-down, it would be great for it to render a select so that when received by a mobile device, the native option selector can take over.  I am posting this in the Web controls for those of us creating responsive apps where the input surrounded by spans doesn't really work out very well when the page is rendered on a mobile browser.  I realize that are trade-offs so maybe instead of completely disregarding the current controls, maybe another, pure control, or some configuration option to the current controls would be preferable. That way, the developer could decide what was more important - the UI enhanced feature or compatibility with device.

Please Add Skin Chooser control

To use Kendo UI as View part of MVP pattern where Model and Presenter reside in GWT it is important to have a GWT wrapper for Kendo UI.

Today, the only way to change the date in kendoDatePicker is to show the calendar and select another date, but in scenarios where i want to allow my user to move one day at a time as defaule, a left arrow and rigt arrow will be great.
same thing holds for the kendoNumericTextBox, althogh he has the up/dowun arrows, they are relitevly small and a Plus and Minus icons to the right and left of the widget will be easier for a fingure to tuch.

Enable the user to show the icon in a different place than the default. like the right of the text and not juts to its left.

I think a Kendo UI plugin for WordPress would be a potentially massive hit with WordPress users and developers. I saw here http://www.kendoui.com/blogs/teamblog/posts/12-02-29/q_a_from_kendo_ui_webinar_q1_2012.aspx that you can use Kendo UI with WordPress. That is great, but an actual plugin would be awesome. Of course there are plenty of ways you could go about it - these are just a couple broad suggestions that come to mind. Offer a free WP plugin available to current Kendo UI customers seeking simplified integration with WP. Or, offer a premium/paid WP plugin to potential customers who would like to use Kendo UI with WordPress site(s) only. 

you can able to change background image in kendo ui slider.

Take a look at DevExpress DXperience...

You can currently set series labels to position "center" on the pie chart to get them to render on the slices, but sometimes slices are too small to contain these labels. It would be great if there were an option for the chart to detect when a slice is too small and render the label outside the chart, while still rendering labels on pie slices that are big enough to contain them.

For these tools to create ID's for all actionable items and allow them to be named(Telerik's Default)or by the developer as the developer creates them.