When disabling transform axes in the pose mode sidebar, the transform
manipulator would hide the matching axes. However, the sidebar always
acts in local space (so locks the local axes), whereas the manipulator
may show a different space.
It can be highly confusing to use the manipulators in global space now,
as the hidden axes do not match the actually locked ones.

For demonstration's sake:

• Open this .blend
  transform_manipulators.blend535 KBDownload
• Note that all axes exept Y are locked
• Drag the Y axis
• Confusingly, nothing changes because local Y axis was locked, manipulator shows global

Note that this change was suggested to me by animators here in the
studio (Blender Animation Studios).
Also note that there's a weird behavior when all translate axes are
locked: dragging an axis rotates then. Turns out there is explict
transform code to enable rotation when translation is not possible.
We may want to disable that behavior for the transform manipulator.

While the same issue can be reproduced in other modes, it's less
confusing there as both the sidebar and the manipulator use global space
by default here.