The control's performance is low and in most cases the application hangs when you try to reset the control's zoom to its initial state. This happens in a scenario with big period range (for example 2 years) and when a MinuteInterval is defined. When you zoom-in to a level where the minutes are displayed and then you try to zoom out with the scrollbar (or if you change manually the VisiblePeriod to match the PeriodStart and PeriodEnd), the application hangs.

Workaround:
Remove the MinuteInterval from the Intervals collection just before changing the VisiblePeriod and then add it again in the collection. 

private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
    var interval = _timeline.Intervals.FirstOrDefault(i => i is Telerik.Windows.Controls.TimeBar.MinuteInterval);
 
    if (interval != null)
    {
        _timeline.Intervals.Remove(interval);
    }
 
    _timeline.VisiblePeriod = new SelectionRange<DateTime>(_timeline.PeriodStart, _timeline.PeriodEnd);
 
    if (interval != null)
    {
        _timeline.Intervals.Add(interval);
    }
}

If the RadTimeline control is placed in a DataTemplate and the ItemTemplateSelector property is set in XAML, the selector is never used.

This is not reproducible if the RadTimeline control is not in a DataTemplate.

To work this around set the ItemTemplateSelector property in code-behind, after the RadTimeline control is initialized. You can use the Loaded event of the control.

If you click on the collapse/expand button of a group (when the data is grouped) while you add or remove an item from the ItemsSource of RadTimeline, all items disappear.

To work this around set the AnimationManager.AnimationSelector attached property on all TimelineItemGroupControl elements to null. You can do this using an implicit style.

 

The UI hangs when a custom interval (deriving from IntervalBase) is implemented and specific values are returned in its abstract method implementations.

WeakListener objects are retained in memory when the view is refreshed. 

When the models populating the ItemsSource of the RadTimeLine implement the INotifyPropertyChanged interface, TimeLineDataItem objects are retained in memory. 

The theme foreground is not applied on the group header when the theme is applied with StyleManager

For example: The foreground for the Expression_Dark theme should be #FFDDDDDD, but instead it is #FF000000

The theme is not propagated to the TimelineStripLineControls when it is set on the timeline control with StyleManager. Which leads to the color of every second strip line using the default color for the Office_Black theme