I was looking at commits-list, and noticed 7bc750a5861fb72c1f24664b17f0cb0799077dc1.

You changed
timeout_dim /= IDLE_DELAY_TO_IDLE_DIM_FRACTION
(timeout_dim /= 3)
to
timeout_dim *= IDLE_DELAY_TO_IDLE_DIM_MULTIPLIER
(timeout_dim *= 4/5);

but that resolves to
timeout_dim = timeout_dim * (4/5) = timeout_dim * (0) = 0;

You need .0 to force double conversion, or to write
timeout_dim = timeout_dim * 4 / 5
to get the multiplication first