In Xamarin Forms there is a serious need for a Rich Text Editor control that would allow you to do this such as highlight text, apply fonts, styles etc. I think a tool like this is in great demand among Xamarin developers. Currently there are some Open source controls that have implemented these features however they have not been maintained and cannot be relied on for enterprise solutions

Applications that are built with AndroidX are currently not supported.

On UWP and Android the item can be swiped beyond the SwipeOffset property. Add option to restrict the swiped distance to the SwipeOffset value.

Provide and option to apply a shadow.

Add support for header and footer that scroll with the content of the list view.

A PDF Viewer component that you can put in your app will be a great addition to the suite. As a feature set it should at least support pinch and zoom.

Add functionality to slide through the items like in a SlideView/Carousel.

Add controls to selecting dates/times that also support null or blank values.  Currently the DatePicker control that is provided as part of Xamarin Forms doesn't allow for a null or blank date.
Provide the ability to select date and time in single UI.

The Source property should support two way binding.

Available in the R2 2018 release.

Currently in RadAccordion one accordion item is always expanded.  I would need the option the accordion to be fully collapsed. In addition, when the header of an expanded item is clicked, it should be collapsed.

A GridView control will be a great addition to the suite. It should offer:
- Multiple columns
- Sorting
- Filtering
- Grouping
- Conditional Formatting
- User interactions

Available in the R3 2017 release. More information you can find here: http://docs.telerik.com/devtools/xamarin/controls/datagrid/getting-started/getting-started

The TabView control should support a swipe event to change the active item. Similar to the ListView with the IsItemSwipeEnabled-property.

Introduce a MaxLength property. 

An example of such a feature is the Xamarin.Forms Entry control's MaxLength property: 

https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/text/entry#limiting-input-length 

Add support for ListView item template selector.

Available in minor release 2017.2.0721. It will also be available in the R3 2017 release.

Most PDF Viewers come with the ability to print, email, text etc the PDF that is loaded.  For example, in the default iOS PDF viewer there is a "share" icon.  When the "share" icon is tapped, multiple options and apps come up that allow users to "print", "message/text", "email" the PDF.  It would be a great feature to have in the Xamarin UI PDF Viewer.  It could just be part of the PDFViewer Toolbar options.