This is the cutest wish list I've ever received 
I added your requests to our infinite to-do list (https://neuroimage.usc.edu/brainstorm/Next#Recordings) and will keep your drawings on the side.
- For your initial request: I will not work on this in the immediate future. Hopefully the threshold detection will work for you. You can also add horizontal lines to the figure (in the new display options menu at the bottom-right of the figure).
- Ruler: This should not be too complicated to code. In the meantime, have to noticed that if you select a time window, it shows at the bottom the duration and min/max values? If one or several channels are selected, it gets the min/max only from the selected electrodes.
- Counting: this is probably easier to compute from a script, as it will probably be difficult to generalize. Or maybe there is something that can be done with the processes that combine events: Combine stim/response, Remove simultaneous, Group by time. Maybe they don't work with extended events, but I could fix that. The idea would be create new categories of events with the list of 20 or 30s pages that contain your marker of interest. Does it make sense? Let me know if I should do any adaptation to these processes for this purpose.
- Splitting a signal in multiple frequency bands: this is something that has been requested a few times before. One solution would be to add an extra option for filtering each signal in the montage editor (similarly to the color: https://neuroimage.usc.edu/brainstorm/Tutorials/MontageEditor#Custom_montage), this would allow to display as many frequency bands as you want from one of several sensors. Will work on it at some point, but don't know when...
- Could you send me pointers or code for one (or more) detectors you'd like to see in Brainstorm?
Thank you for all these nice suggestions!
Francois