Now that 2_05_01 is BETA, I finally got around to taking a look. First up, I lost all my saved graphs 
but that’s not the point of this topic. As I tried to recreate my old graphs (to mirror PVOutput and Solar Analytics and Fronius Solar.web graphs), I noticed that the tooltip is only reporting the sum of a stacked item and all items below it in the stack.
Say I have air con which is using 30W and power points that are using 150W and lights using 20W, and I stack these in Graph+. When I hover over the graph to see the value at a given point in time for air con, I instead see the sum of the whole stack (200W, air con is “on top” of the stack). For power points,
I see 170W, and for lights I see 20W.
Ideally, I should be able to see a “total” for the whole stack and each individual item in the stack, in the tooltip.