Programmatically expand/collapse Timeline Groups?

[James]

I have used the information at http://www.telerik.com/help/wpf/radtimeline-features-grouping.html#ChangingExpandableGroupsCollapsedState to set up the default values for expand/collapse*

I would like to add "Expand All" and "Collapse All" buttons to my page for the user's convenience, however, I can't find a way to do this; is it possible?

*: I have the style set so that all groups start expanded, but oddly, the first time the timeline draws data, the first group is NOT expanded even though the rest are.  After this first time, everytime I change the collection bound to ItemsSource, all groups will be expanded

[Tsvetie]

Hello James,

Indeed, currently, there is no easy way to control the expand/collapse state of the timeline groups. We have already added this task to our ToDo list. The only approach that I can offer you, is the one we use in our Grouping demo. Basically, we use an attached property to change the IsExpanded property of the groups.

Regards,
Tsvetie
Telerik