@bronedooy That doesn't even require a mod. This from old forums: https://forums.faforever.com/viewtopic.php?f=2&t=8230
Just edit your preferences file.
If you can't work it out yourself ill post them later (but I'd prefer not to pollute Ctr-K's thread).
e.g. add a block like this to UserKeyActions section of your prefs file:
['Select T1 idle engis on screen'] = {
order = 2,
action = 'UI_SelectByCategory +inview +idle BUILTBYTIER1FACTORY TECH1 ENGINEER',
category = 'All land onscreen'
},
Edit out "+idle", increment the order number (don't have two the same in the same category) and change the category as you see fit. The category affects how the definable key will appear in the key bind window. Amend the TECH level and BUILTBYTIERXFACTORY as appropriate. Oh and back up your prefs file first. Apologies for the hijack....nice mods!