How can I get a trigger to change the color of a TextBlock based on a DataContext Property?

Question

Why does the following code get the runtime error:

Members of the Triggers collection must be of type EventTrigger

But the Event

Answer 1

That is because you can only set event triggers directly on the Trigger property..

Use a style to achieve what you want:

The following objects have Triggers collections that can contain the trigger types listed:

FrameworkElement     Style, ControlTemplate, DataTemplate
----------------     ------------------------------------
EventTrigger         EventTrigger
                     Trigger or MultiTrigger
                     DataTrigger or MultiDataTrigger