Kendo UI supports PDF export. It would be great if you could add glyph mirroring support to it as well (https://github.com/mozilla/pdf.js/blob/master/src/core/bidi.js). PDF export of RTL languages such as Arabic and Persian need this trick to work properly.

It would be a great help if there was a way to add a Trendline to a line chart in the DataViz collection.  This function is available in excel and other similar programs.  
The wiki page explains:
http://en.wikipedia.org/wiki/Trend_line_%28technical_analysis%29

Please think the Kendo UI validation farmework not only in terms of client-side validation but also in terms of reporting server-side errors.

A framework that would only provide a way to display a validation error message based on a client-side rule after each related input field would not be very helpful in my opinion.

All errors need to be reported in a consistent way. My preferred option is:
- a message box at the top of a form to display all messages including OK messages and error messages (client-side and server-side).
- higlighted fields with tooltips (not to clutter the form layout) to repeat error messages in context when applicable.

Although the framework built into Kendo UI might only provide client-side validation, please make sure to provide entry points into the UI used to report errors. Alternatively, leave the UI to the developer and provide a simple way to collect all validation error messages on a form.

Check out this idea. It may help solve this issue and help with UI presentation.
http://feedback.kendoui.com/forums/127393-kendo-ui-feedback/suggestions/3767009-treeview-in-combobox

Admin edit: A Knowledge Base article that shows how you can achieve this: https://docs.telerik.com/kendo-ui/knowledge-base/disable-multiselect-items

Suppose a model is defined with settings for editable, required, validation, etc. Then this model is used a datasource's schema.

Instances of the datasource's data will be models. However, if a model is bound to some HTML view, it's settings are not applied to the view. All settings have to be manually applied to the HTML elements.

I suggest that these settings are applied automatically. Then for example, a field's property like "required" wouldn't have to be coded at two different places.

It would be really nice to have an easy way to dynamically create Kendo Windows in AngularJS. And also with separate controller and template.

https://github.com/kjartanvalur/angular-kendo-window

Here i´m trying to do this but it would be really good to have a similar way integrated into Kendo. There is also a demo on the repo.

http://plnkr.co/edit/6lyrblMhZ5ofuonmGoPZ?p=preview

Allow to sort an ObservableArray

The current work around is to use the native array function

Array.prototype.sort.call(myArray, myComparer);

Right now there are two options for sorting, single and multi-column. We would very much like to use the multisort version, however our users fail to understand the functionality. We suggest a new setting, "ctrl-multisort":

Single-sort when clicking and multi-sort when ctrl-clicking, similair to most desktop grid controls.

A heatmap (grid-style at least) is very much useful in any decent project management application. A widget that could remotely connect color-shades to jSON data would be really great.

Textbox control which keeps extending until we finish typing.
something like what iOS have when we want to add note in contact.

Once created, many Kendo components root DOM element are wrapped under new HTML elements.  Any class of the original input will also be copied to some parent elements.

As each widget (DateTimePicker, DropDownList, ComboBox...) are wrapped differently, it might be a good idea to add a class to the root input (k-root) that would allow us to search for that specific input.

See this post for more details:
http://www.kendoui.com/forums/ui/general-discussions/best-way-to-find-the-root-element-by-class.aspx

Please add option for setting custom window titlebar icons like in this Telerik MVC Window example:

http://demos.telerik.com/aspnet-mvc/razor/window/loadingexternalpage

The new funnel in the Q3 release is great, but it looks very flat.
It would be great to have a more 3D look.

Your silverlight Timebar is Briliant.

I suggest you implement something like that(maybe a litle less complex) in KendoUI.

Personally, I much prefer image buttons over text buttons in the grid just to keep bulk down especially when you have a wide grid or a number of custom command buttons with long text.

To do this at present requires some fancy css styling in the grid databound event.

I would like to see more configuration options for grid commands to allow for ....

- Built-in commands (Edit, Delete, etc) and custom commands to be image only
- Built-in commands and custom commands to have a "tooltip" option

It would be very useful from a visual and functional perspective to be able to view scheduler items in a year view, that seems to be currently unsupported.

I have a list view of unassigned users, I can drag and drop from listview into a treeview to assign them to a group node in the treeview. (This works) I need to drag multiple items to the same group node to add more than one person at a time.

multiple draggables to one dropTarget.

I would love to see this happen in the next release! The hacks out there work, but we're still forced to use the Select2 library to do this well. We want to use Kendo for the whole project.

We are needing the virtual scrolling to work for our project and also need the detail rows working. The explaination of the problem was described on the forums here:
http://www.kendoui.com/forums/ui/grid/hidden-detail-row-when-using-detail-template-and-virtual-scrolling.aspx

Add the ability to display the Show/Hide Column menu by right clicking the Column Header instead of going through the "Column Menu".

It would also be nice if you could access the Filter directly instead of going through the "Column Menu"

The current Column Menu unnecessarily hides functionality in a menu  that should be more easily accessible.