Area tool to set a specific/high priority

Priority settings are huge in this game, but they're very inconvenient to use.
There are several general issues, most notably - it's easy to confuse the operational priority and construction priority. I often want to build a new set of buildings with high priority but end up setting their operational priority to 1.
A good solution would be a better area tool that allows selecting the desired parameters and type of priority, and then I can just drag the tool over the buildings.
It's also useful because connected belts, lifts, etc. also have priority, but it's so hard to manually change their priority one by one. Otherwise, in some critical cases, some random belts would work to carry the slag instead of carrying the maintenance.