I created a generic useless control with a virtual property:
public abstract class TestControlBase<TValue> : Control
{
public static readonly DependencyProperty ValueProperty;
static TestControlBase()
{
ValueProperty = DependencyProperty.Register("Value", typeof(TValue),
typeof(TestControlBase<TValue>));
}
protected TestControlBase()
{
Focusable = false;
Value = default(TValue);
}
public virtual TValue Value
{
get
{
return (TValue)GetValue(ValueProperty);
}
set
{
SetValue(ValueProperty, value);
}
}
}
Then I created a managed item and overrided the Value property:
public class TestControl : TestControlBase<int>
{
public override int Value
{
get
{
return base.Value;
}
set
{
base.Value = value;
}
}
}
Therefore, I use it in Window XAML:
<TestControls:TestControl />
When I open a window in the designer, everything is fine, but when I place the mouse cursor on this line or on this control in the constructor, I get an exception:
Exception has been thrown by the target of an invocation.
at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Delegate.DynamicInvokeImpl(Object[] args)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
Ambiguous match found.
at System.RuntimeType.GetPropertyImpl(String name, BindingFlags bindingAttr, Binder binder, Type returnType, Type[] types, ParameterModifier[] modifiers)
at System.Type.GetProperty(String name)
at MS.Internal.ComponentModel.DependencyPropertyKind.get_IsDirect()
at MS.Internal.ComponentModel.DependencyPropertyKind.get_IsAttached()
at MS.Internal.ComponentModel.APCustomTypeDescriptor.GetProperties(Attribute[] attributes)
at MS.Internal.ComponentModel.APCustomTypeDescriptor.GetProperties()
at System.ComponentModel.TypeDescriptor.TypeDescriptionNode.DefaultExtendedTypeDescriptor.System.ComponentModel.ICustomTypeDescriptor.GetProperties()
at System.ComponentModel.TypeDescriptor.GetPropertiesImpl(Object component, Attribute[] attributes, Boolean noCustomTypeDesc, Boolean noAttributes)
at System.ComponentModel.TypeDescriptor.GetProperties(Object component)
at MS.Internal.Model.ModelPropertyCollectionImpl.GetProperties(String propertyNameHint)
at MS.Internal.Model.ModelPropertyCollectionImpl.<GetEnumerator>d__0.MoveNext()
at MS.Internal.Designer.PropertyEditing.Model.ModelPropertyMerger.<GetFirstProperties>d__0.MoveNext()
at MS.Internal.Designer.PropertyEditing.PropertyInspector.UpdateCategories(Selection selection)
at MS.Internal.Designer.PropertyEditing.PropertyInspector.OnSelectionChangedIdle()
Who knows this problem? Please explain :) I have no ideas, except that WPF Designer does not like generics. If you replace generics with Object, everything will be OK.