A confirmation dialouge for every steal is not ideal, it will get tedious fast. An on/off option for this is better but wont solve the problem for those of us who want to turn the confirmation dialogue off.
How about only allowing the player to steal items when s/he is in sneak mode? This should mitigate the risk of a accidental steal significantly, especially considering that the player will be much more attentive once having made the choice of going into sneak mode in the first place. A quick "you must be in stealth mode to steal this item" popup should be enough to inform players of the mechanic.
This of course depends on the player being freely able to go into sneak mode. So on a slightly unrelated note: Please allow players to go into sneak mode even if npc's can see them. I had the seeker following me after saving him from the magisters in the ruins and was unable to sneak because he "spotted me" all the time, even though he was tagged as a friendly.
I need to emphasize this again: there's a reason I said alt + click should disable confirmation because throughout my entire playthrough of DOS 1 I don't recall a single instance where I decided to consciously steal something without holding down the ALT key first. I am also not quite sure why you think an on/off option won't make you happy. If it's set to off it's literally exactly the same like what we have right now, ie no confirmation whatsoever.
As for entering sneak while under friendly sight cone, that might be a problem because people can then steal anything from a friendly NPC with impunity by simply entering sneak whenever where ever. In your case, it's easier to just break formation with your rogue and have him entering stealth somewhere else. Unless the seeker happens to be following your rogue of course.
