It’s nice to have control over the source shape of a light for reflections, however the light itself always emits from a sphere shape (spot&directional aside). Additional emitter shapes like a non-uniform scalable plane [arealight] and capsule [tubelight] would be great to have!
Tube lights are available with Beta 5. You can adjust it with Source Length.
As I wrote, this only affects the shape of the reflection, the light itself is still being emitted from a spherical shape rather than a tube shape.
Hi Christian,
I have entered a report for your Feature Request.
Cheers!