Suggestion: Structures that prevent pyratite combustion. E.g. armored and/or cooled conveyors.
Suggestion: A feature like Ctrl-drag to automatically junction with conveyors/conduits, wrap around structures, and bridge over structures.
Suggestion: A feature to list the aggregate production of a set of structures. An amount that assumes the production structures are properly connected would be useful, and would avoid having to figure out how well the conveyors/conduits etc are working. For example, draw a box around a bunch of drills, to learn that they produce 5.8 coal per second; or click on a bunch of powered pumps, powered drills, and steam engines to learn that they produce a net 980 power, 30/s water, and 3.2 coal per second.
Suggestion: A feature to list the aggregate production shortage of a set of structures. For example, select some drills and graphite presses, to learn that they need .67 more coal per second to operate optimally.
Suggestion: A feature to list production in the build menu, as X.Y units per 1 second, rather than the current X units per Y.Z seconds. This would help with math to balance production (without constantly switching to a calculator or doing mental arithmetic).
Suggestion: A feature to list how many structures of a given type, are needed by a structure of another type.
Suggestion: A feature to list how many structures of a given type, are needed to meet the aggregate production needs of a set of structures.
Suggestion: Normalize all fluid production amounts in the build menu, to all either show N/sec of fluid, or N per production time. For example: Cryofluid Mixer lists input as 24 water with a Production Time of 2 seconds, while Plastinium Compressor lists input as 15/sec oil. I'd prefer the N/sec listing, so Cryofluid Mixer's input would just list 12/sec water (unless it really means 24/sec water).
Suggestion: Improve unbuilt structure queue, to avoid unintentially losing unbuilt structures. For example, if I queue two structures having none of their resources, their "shadow" remains, but if I right click too many times, it disappears. Given that right clicking is needed to switch to fast-flying or combat. I shouldn't have to count my clicks very meticulously just to avoid losing a large build queue, particularly when I need to fly away quickly for combat. Maybe have two separate inputs, one for clearing the queue, and one for temporarily releasing the queue to do something other than build. This would also make it easier to multi-task building and combat.
Suggestion: Improve queue to prioritize new structures that actually have resources available, instead of focusing on one structure that cannot be built while others in range could be. Optimally, a selected or nearest structure would still be given priority, when new resources become available.
Suggestion: Allow re-queueing of multiple partially-built structures. For example, I have two partially-built structures and clear the queue, then I must manually click on each to complete building. It would be better, for example to drag a box around them, and re-add all to the queue.
The two functions are "Deselect" and "Break Block". Like you, I find these two functions both work well on the same right-click. Still, that doesn't address the 9th suggestion. That suggestion is about how "Deselect" basically also performs a "Clear Construction Queue". If there were a third input for Clear..., I'd gladly remap that.