RadExpander IsExpanded binding problem

[J]

I have an expander that contains sub-expanders. I want to automatically close the sub-expanders when I close the main expander. I have implemented this logic using data binding, but it doesn't seem to work correctly.

Looks like binding to the IsExpanded property gets destroyed after you close the expander using the expander's button. Have omitted a call to the SetCurrentValue method...?

Example project attached. See the ReadMe.txt for details.

Pretty frustrating that you don't allow attaching archives. Doesn't encourage that much creating example projects. Your ticket system is a pain in the donkey if you are a consultant. Things could be done more easily and efficiently.

Anyways, here's a Google Drive link to download the project: https://drive.google.com/drive/folders/1JvBukVvfmxWsRW5Wb-nRXbT5a6EOWvCd

Let me know when you have downloaded it so I can delete the file.

[Martin Ivanov]

Hello J,

I downloaded the project, so you can delete it from the storage. Kudos for the good steps to reproduce the issue.

Setting the value of the SubMenuIsExpanded property doesn't work because of the binding mode set for the IsExpanded property binding. Basically, the IsExpanded property of the RadExpander control is bound with TwoWay mode in its ControlTemplate to the IsChecked property of the internal toggle button that handles the UI expand/collapse interaction. This is similar to setting a local value to the property which has a bigger priority than a binding with Mode=OneWay. 

In order to resolve this you can set the Mode of the binding to the SubMenuIsExpandedProperty to TwoWay.

<telerik:RadExpander IsExpanded="{Binding SubMenuIsExpanded, Mode=TwoWay}">

I hope that helps.

As a side note, the indeed the forum doesn't allow .zip attachments. Instead you can use the ticketing system to open a new support ticket.

Regards,
Martin Ivanov
Progress Telerik