WPF Error Styles only being rendered properly on visible tab of a tab control

Question

I have a data object used to contain my UI data that supports INotifyPropertyChanged and IDataErrorInfo. Originally I had all of the UI controls di

Answer 1

(I am using the AdornerDecorator as I had experienced in a previous program the error style not being re-rendered when swapping tab pages. I can't remember where I saw this but it did help me out)

Presumably this indeed important tip originates from Karl Shifflets blog, at least he's addressing the same topic: WPF Validation Errors Disappear Inside TabControl When Switching TabItems.

Given this your issue might just be related, i.e. the tip/code above ensures there is a dedicated AdornerLayer for every tab item now, as the adorner layer of the parent element is discarded when you switch tabs. This dedicated adorner layer appears to still require some special treatment though, see for example question WPF ErrorTemplate visible when not focused? which is basically dealing with your issue upside down. Consequently I'd suggest you combine and expand the outlined solution for the latter with your style and try the following (untested code as of now though):

See my comment regarding your update of Radio Button Error Style too, which tries to similarly address your likely related question; have you actually tried my suggestion there?

See Adorners Overview for more details on the adorner architecture.