When I build tracks and signals, I have to click often on signalboxes, just to switch between them so that the signals are assigned properly. I'm not that much interested in the info about the signalbox itself, the most important is which signals become available to me. So it would be nice if the first click on signalbox opens the rail building toolbar, and only the second click would bring the info about signalbox (capacity, range, employees, etc)
I think that opening the building window when clicking the signal box for the first time would be counter-intuitive, as that is very different from how all other buildings behave, instead giving info windows. Having the track tools opening on the second click might work (although is not a priority), but has this particular difficulty: signalboxes do not have a waytype, and a single signalbox can work with multiple waytypes (e.g. standard gauge and narrow gauge track), so which specific toolstrip to open would not be able to be inferred from any data in the game (except, perhaps, by somewhat cumbersomely checking which signals are linked to the box and then checking which waytype that they use, but this would not work for newly built signalboxes with no signals yet).