16. December 2010 14:39
Update: this issue is now posted to Microsoft Connect. Please vote for it.
I found a very interesting bug in WPF concerning validation on controls that were previously collapsed.
This example shows a bug that the validation border does not work when a bound control is made visible and then set an error on that control.
If you make a selection in the combobox, the details part will become visible (the details contain errors, but they are not visible). The 2nd time your change the combobox from "No details" to a value, the errors will become visible).
It's not that WPF doesn't know that the control contains an error, because even when the red border is not visible, the tooltip containing the error is available (just hover the empty textboxes).
ValidationProblem.zip (1.19 mb) [Downloads: 438]