creation of a line graph on a scatter point chart with gaps in the line when expected values are missing 

Something like this:

Currently the only way to apply different colors to the bars is through the ChartPalette. Provide an option to set the color according to the bound data item.  

when applying the filter in a column where the scroll is on the right, all the scroll is reset to the left and the popup moves to another column. 

Data can come dynamically from JSON, XML, and SQL.  Without the ability to bind a grid to commonly used structures (like a Newtonsoft JSON, .NET DataTable or Dictionary), this grid has VERY limited use for apps that use modern ways of gathering and managing data (like JSON-Schema).

When you are in tablet mode and try to type 6 from the on-screen keyboard - the "-" sign is applied. 

Provide a tabstrip control that allows users to display content on tabs.

 - Tab content could use virtualization to avoid extra rendering
 - Follow themes from Telerik
 

When the RadNumericBox has focus it displays a clear button on the right, the "X".  In a high data density screen or grid, space can be at a premium and this button takes space, and when the user has a keyboard is not necessary (they can use the delete key) It would be space saving if this button was optional (as per the WPF version).

Universal combo box.

Add a setter for the AutoCompleteBox's SelectedItem property.

For example, to use different keys than the default arrow keys to switch from day -> month -> year in DatePicker

Enable drag and drop between cells of different rows in the DataGrid for UWP. Or a way we can develop it ourselfs.

When the DataGrid is grouped, show the column headers in the group header and allow for aggregates like Sum

It should be similar like the RealizedItemsVerticalBufferScale, but to work for the horizontal part of the ViewPort.

A docking control similar to what is available in UI for Silverlight.

Implement a feature which will allow users to change the trigger which updates the source in Editing Mode

Allow the user to define axis ticks origin value. E.g. with Min=-10, Max=100, MajorStep=25, the user should be able to define that the axis will have ticks and labels at 0, 25, 50, 75 and 100 while keeping the minimum value of -10 in range.

Provide API or another approach to achieve synchronized trackballs.