Comments by Member 13324229 (Top 1 by date)

Thank you very much for the answer. However, there is a misunderstanding here. The goal is when you drag the MyLabel from toolbox and drop on xaml UI, must be generated the MyControlGuid="6c090537-4a06-41d5-a0ea-6d3112df0f77" on xaml file. Under Property Grid for ui control contains already the right guid, but is not on xaml file. Only when you convert manually to local value over Visual Studio - fill the MycontrolGuid on xaml.

We can discuss which is better set Guid over clr Property or SetValue to Dependency Properties but boths ways make no difference for writing on xaml.

MyControlGuid should be behavior like Content or HorizontalAlignment of label and must be autogenerated on xaml by dropping on ui.