OneWayToSource Binding seems broken in .NET 4.0

Question

OneWayToSource Binding seems broken in .NET 4.0

I have this simple piece of Xaml

Answer 1

This is quite clearly a bug. It seems to have been reported at least once by someone. https://connect.microsoft.com/VisualStudio/feedback/details/612444/onewaytosource-broken-in-net-4-0

I agree with many of the others that one way should be one way period.

My scenario is complicated and having functionality changed between framework versions has caused me a real headache.

I have a textbox bound to a property. I have a converter which changes the format on the fly. EG: I enter EU5 in the textbox, the property gets EU005. I have got the binding set to trigger on property changed as I need to do lookups within the ViewModel as the user types. The new implementation changes the value of the textbox as I type. So if I wish to type EU512 I couldn't easily as the textbox text would keep changing.

I have tried many thing - Explicit binding (where you decide when to update and which way.) This has the same problem. If I say, UpdateSource, it does, but also then rereads the property and changes the target too.

I tried OneWayToSource and had the same problem. I have found no way to work around this without making annoying changes to my VM. The only other way would be to remove binding on this field and start firing events which would be awful.

If MS made the binding behave as it is logically named then my problem would disappear. Even a property on the binding to opt out of the .net4 implementation and behave as 3.5 would work for me.

Anyone have any suggestions for me on how I can get around this?