[NTG-context] overbar in math mode is asymmetric over "F"

Hello, the following small sample illustrates the problem: \starttext \enabletrackers[math.stackers.texts] \math{\overbar {ABC}} %<-- somewhat okay \math{\overbar {F}} %<-- too short on the right side %manual fixing \math{\overbar {ABC\mkern\onemuskip}} \math{\overbar {F\mkern3\onemuskip}} \stoptext I wish to have an overbar that extends over the exact boundingbox of the letter or sequence of letters. How can this be done in context without manual fixing? Thnk you, Bernd Donner