When you have declared a RadTabView with a single item and you try adding items at runtime - the new TabViewItems are added to the Items collection of the control but the UI is not updated.
Allow different width tab headers. For example, 200, 100, 100. Available in minor release 2018.2.727.250. It will also be available in the R3 2018 release.
This feature request asks for the option to align the TabViewItemHeaders to one side of the HeaderPosition, using the minimal amount of horizontal space (rendered as if they're in a horizontal StackLayout) As a good example, the UI for WPF TabControl does this, notice the tab headers are left-aligned: https://docs.telerik.com/devtools/wpf/controls/radtabcontrol/overview2
Support for interactive TabHeader content (i.e. Buttons, Checkboxes) that does not invoke the tab selection and is aligned next to the tabs
We should consider adding one or more events related to the selection of the TabView control.
Introducing a TabItem.IsTabVisible property would be useful. Currently, if you want to hide a tab, you need to remove it from the TabView.Items collection and cache it in a backing collection. Then, to re-show the tab, remove it from the cache and add it back to the TabItems (preferably at the same index if you've also cached it's position).
At the moment when clicking the overflow button, a list of items is displayed in a Popup. It would be convenient if there is a built-in mechanism for defining a custom action upon clicking the overflow button. For example one might want to open a SideDrawer.