Kerbal Space Program

The advanced SAS "target tracking" feature (Target and Anti-Target) is unselectable when the current craft's speed relative to the target is zero (or very close to zero). This can make approaches a bit frustrating, as each time I null out my relative velocity I have to manually find and center the target marker on the navball again.

To reproduce:
1) Have two vessels close to each other in orbit, at least one capable of SAS target tracking (e.g., with an RC-001S Remote Guidance Unit).
2) Select the vessel with target tracking as the current vessel.
3) Target the other vessel.
4) Null out velocity relative to the other vessel.
5) Activate SAS.
6) Observe that the Target and Anti-Target SAS options are not selectable.