[IronPython] Silverlight - Cannot save value from target back to source

[Lukas Cenovsky]

  Following my binding experiments in WPF, I tried to convert the sample 
into Silverlight and I hit another binding errors there.

When I bind anything else than string, I receive an error when the 
target value is changed and the source should be updated. This happens 
in all IronPython versions (2.6.1 on .Net 2.0 and 4, 2.7a1).

Here is the code I use (the whole source is attached):

     @property
     @clrtype.accepts()
     @clrtype.returns(System.Nullable[System.Boolean])
     def filtered(self):
         return self._filtered

     @filtered.setter
     @clrtype.accepts(System.Nullable[System.Boolean])
     @clrtype.returns()
     def filtered(self, value):
         self._filtered = value
         self.OnPropertyChanged('filtered')

As you can see I tried to use System.Nullable[System.Boolean] instead of 
bool but it did not help. I also tried to use converter and convert the 
value to this type (System.Nullable[System.Boolean](value)) but that did 
not help either. All resulted in the following exception for bool type.

System.Windows.Data Error: Cannot save value from target back to source. 
BindingExpression: Path='filtered' DataItem='Mountains' 
(HashCode=2058916); target element is 'System.Windows.Controls.CheckBox' 
(Name=''); target property is 'IsChecked' (type 
'System.Nullable`1[System.Boolean]').. 
System.Reflection.TargetInvocationException: Exception has been thrown 
by the target of an invocation. ---> 
System.Security.VerificationException: Operation could destabilize the 
runtime.
    at Mountains.filtered(Nullable`1 value)
    --- End of inner exception stack trace ---
    at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo 
method, Object target, Object[] arguments, SignatureStruct& sig, 
MethodAttributes methodAttributes, RuntimeType typeOwner)
    at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, 
BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo 
culture, Boolean skipVisibilityChecks)
    at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, 
BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo 
culture)
    at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object 
value, BindingFlags invokeAttr, Binder binder, Object[] index, 
CultureInfo culture)
    at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object 
value, Object[] index)
    at System.Windows.CLRPropertyListener.set_Value(Object value)
    at System.Windows.PropertyAccessPathStep.set_Value(Object value)
    at System.Windows.Data.BindingExpression.UpdateValue().

The similar exception is raised for float or System.Double.

I have found an old issue similar to this: 
http://ironpython.codeplex.com/workitem/16831?ProjectName=ironpython

Any workaround would be nice for this bug :-)

--
-- Lukáš
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