I am not sure if this is intended behavior, or if it is actually a bug/oversight, but I would like to request the 'zoom out' tool zooms out from the CURRENT POSITION, by one zoom increment (so just the reverse of how the zoom in works using the mouse scroll wheel). This would keep the zoom in/out consistent with how the GeoPlan zooming works.
If you 'zoom in' to a graph (with the mouse scroll wheel or the 'zoom in' tool), and then pan across to a different time, and then try to 'zoom out', it doesn't work as expected. Rather than zooming out from the current position by one zoom increment (so just the reverse of the 'zoom in' operation), it doesn't technically zoom out at all - it actually just jumps to the 'previous view' from immediately before you last zoomed in (however long ago that was).
I am finding this quite frustrating at the moment since I am verifying a model using a full-survey-period simulation, and am continually zooming in and out and panning across to various storm events, but each time I zoom out, the screen jumps back to where I zoomed in from, which makes the experience very clunky and jerky.
I raised this a few years ago but I have been disappointed to find that each time we have upgraded ICM to a later version that this still hasn't been addressed. In GeoPlan, the right mouse pop-up menu has a 'zoom in', 'zoom out' and 'zoom previous' so the code is in ICM, it is just that it hasn't been implemented uniformly. I would say that it is very rare to need to use 'zoom previous'.
In the same vein of (non-)uniformity, to zoom-in GeoPlan, the F9 key sets zoom-in, and F10 sets zoom-out but in custom graphs neither keys work. (These function key assignments date back to HydroWorks!). I never click on the zoom-in button in GeoPlan; I always use F9.