In the JQuery Grid if you have the following column definition (for example):

[
    {
        "field": "Name",
        "title": "Name"
    },
    {
        "title": "Address",
        "columns": [
            {
                "field": "Street",
                "title": "Number & Street"
            },
            {
                "field": "City",
                "title": "City"
            },
            {
                "field": "PostCode",
                "title": "Post Code"
            }
        ]
    },
    {
        "title": "Contact Details",
        "columns": [
            {
                "field": "Email",
                "title": "Email Address"
            },
            {
                "field": "Phone",
                "title": "Phone Number"
            }
        ]
    },
    {
        "field": "DOB",
        "title": "Date of Birth"
    }
]

When you drag the multi-column header "Address" and drop it over "Date of Birth" the header and it's child columns move as expected but the column headers in the two multi-columns get mixed up.

This only seems to happen when dragging a multi-column past another multi-column in either direction.

Show the text in the filterMenu formatted as the text in the column. More info here: http://www.telerik.com/forums/filtering-html-characters

Currently, when kendo grid is initialized from an  already populated html table, there is then no way to freeze columns as there is no datasource specified in kendo grid initialization.

kendo grid dynamic does not contain a definition for MinResizableWidth throwing this error on resize column ..multiple dynamic gids in my mvc view 

minResizableWidth float
The pixel screen width below which the user will not be able to resize the column via the UI.

Bug: Column Resize Handle not showing on dynamic Grid Columns

The problems are the hidden columns. If you have a hidden column in the grid, you can't resize all other columns after the hidden column. That is a very nasty bug, so please Kendo-UI team make a fix for it.

It would be helpful to be able to format a grids content in a more straightforward manner out-of-the-box. For instance, if a Kendo grid was displaying a typical data matrix like https://en.wikipedia.org/wiki/Triangular_matrix, it would be useful to be able to format by the upper triangular region, lower triangular region, odd rows, even rows, etc.

KendoUI Grid persist row selection state after update a field programmatically via the set method of the dataItem.

When using a template for Grid PDF export, usage of AngularJS scope variables should be possible, e.g. to customize the title.

see https://www.telerik.com/account/support-tickets/view-ticket?threadid=1101276 for more details

When grid column is hidden template code is still being executed. For large data sets with many hidden columns this makes grid scroll slower than is necessary...
{ id: 'Artist', title: Columns.ARTIST, field: Columns.ARTIST, width: '100px', hidden: true,
	template: function (dataItem) //this gets executed even when column is hidden. 
	{
		return someMethodToDetermineArtrist(dataItem);
	}
}

This currently causes the locked columns to not line up with the rest of the grid.  See http://dojo.telerik.com/eZasA/2 and http://www.telerik.com/forums/column-locking-row-heights-not-matching#KsWBJy4lGkafpkwZxUYRVw

I believe drag-drop, resize and reorder functionalities should be accessible using keyboard for people with very poor eyesight.

Add support for canvas rendering to the grid. This will improve performance of the grid considerably.

Part of our testing we have concluded that the current kendo grid is not working well with a number higher than 1000 records as it will become very slow when the user is scrolling the data. In an attempt to fix this the virtual scrolling has been introduced but this breaks the grouping as the number of records displayed do not take into consideration if a group is collapsed or not. Therefore you may end up in a situation where you collapse a group with 100 rows and the grid will not display the next groups as they are not part of the current page (e.g page size 10);



As an example of a canvas based grid see below:
https://github.com/openfin/fin-hypergrid

The grid does not resize properly when placed in css flex containers (http://www.telerik.com/forums/how-to-use-grid-in-css-flexible-box#i5x2DlCtiEyWLXLVRg5U-g)  .  Would be good if it supported css flex, and the new css grid as a bonus

The Grid should be able to easly navigate from rows with the keyboard, and also select them by enter.

When performing a grid refresh, the grid re-renders the all the grid rows. 
I think it would be very efficient to have a choice to render specific, changed rows. 
This is valuable if the grid has many items (200 items for example).

The grid validation does not work well when the grid is part of a complex form containing simple fields and a Kendo Validator.  See this forum thread: http://www.telerik.com/forums/grid-custom-validation-not-shown

The grid validation should integrate better with a form level kendo validator so you can validate both the grid and the simple fields easily.

Allow users to filter with null values

It should be possible to change the width of a grid after it created.
http://www.telerik.com/forums/change-column-widths-after-grid-created

Right now kendo's system for alternating rows is to specify rowTemplate and altRowTemplate.  For any non-trivial row template, this makes for a big ugly DRY violation as you copypaste the entire template just to give it a different css class and leave it otherwise identical.  Any future changes to the template have to be made to both copies, and any potential template issues have to be tested on both even and odd numbered rows.

If rowTemplate received whether it's an alternate row as a template parameter, it would be easy to do common things on alternating rows without ever needing to define altRowTemplate.

Provide build-in support for filtering and sorting for complex columns like dropdown or Autocompelete with dropdown in grid. Bound value consists of complex objects - one for value and one for text of the dropdown. Right now, sorting is based on value and not text. Please provide options to sort based on text. Filtering doesn't work for these columns. It would be nice to have filtering support for these columns.