This really should be fixed (assuming it's a bug) as it seems unnecessary and is very annoying:

If I select a unit and then click anywhere near a dreadnought, they automatically form a group! Which I have to disband before I can continue with my original plan.  IIRC this also happens if a dread is selected and I click on another unit...

I think this has been mentioned before but is one of those things that appears so simple to correct that I have to bring it up again, especially as you've asked for UI comments.

Thanks for the continuing development of this great game.