How to make duration field editable programatically

Hi,

In the RCP UI (RTC client) currently the duration field(or estimate field on the UI)for a work item automatically gets disabled whenever the correction field is updated for the first time.(but the same behavour is not there in the Web UI.)

How can we programatically make estimate field editable irrespective of the change in the correction field.
Once we have got the handle of the Estimate (duration) field
is there any way to set or any other way. Please guide.