This could be added as optional (with a flag set by the addAction command). Making it default will break a lot of existing mechanics.

Good idea!

Well, I suppose the other ticket is the same problem, but a completely different solution suggested, so I'll post it here again:

A possibly better fix would be to de-select the action if it becomes unavailable, and only select the previous/next available action (relative to the position of the removed/disabled action) when the user moves his mouse wheel up/down. That way you still don't accidentally use any actions you don't want to use, but also don't break any existing mechanics (for example - Missions that add 20 actions but only let you see and use 1-3 at any given time).

@galzohar could you give an example how this could break existing mechanics?

I already did. Do you really want some missions to suddenly show you 20-50 actions? Sure it might be a better idea to remove them, but considering that missions are already made with "unavailable actions don't show" in mind, and considering that it is much easier to just use a condition rather than constantly add and remove the actions, you can't realistically expect all unwanted actions to always be removed.

Besides, you will still have a problem when the action you want to use is removed - It will not be grayed out and you will have the same problem you have now. My solution works both for disabled and removed actions, not just disabled actions.

@galzohar

I think what he means is that actions that become unavailable while you are using the action menu become greyed out.

@galzohar I don't follow you. As I understood OP wanted the currently highlighted action to grey out but still stay highlighted but you cannot click on it. This way the order of actions doesn't change if action becomes unavailable so you cannot accidentally find yourself selecting wrong action.

What you're suggesting is to automatically jump to another action, which is going to be as bad if not worse than the current system.

Actually, I think the OP made himself very clear in "Steps to reproduce".

Action becomes invalid and is retained in unclickable state until the action menu is closed.

galzohar suggests that the current action selected disappears when invalidated and no other action would be selected, but the action menu remains open. The invisible cursor would stay at the same position where the invalidated action disappeared, so if you used the mouse wheel you wouldn't have to start from the top.

I think the OP's idea is less confusing.

What Fireball said.

As long as all other actions disappear normally and the "grayed out" action disappears as soon as it's de-selected it should be good.

Graying out the invalidated action would also help with small, hard to point, hotspots (are they called that?). You could click it as soon as it becomes valid again after you missed it first time around.

This and removing weapon selection/reloading from action menu would make it much better with very little effort.

Just removing stuff from the action menu is not possible in most cases. For example the game does not limit the number of different magazine types a player can carry, so you can never really work around it with a simple key binding. Even for something like changing to launcher, when PR:A2 tried removing it from the action menu it caused a lot of confusion with people not knowing how to select their launcher. I also know a lot of people who have no clue you can bind a key to "get out" and "eject".

Letting us remove these specific options (that have a matching key binding) from the action menu is OK, but removing them completely will cause too much confusion, and in the case of magazines lose functionality as well.

What you're describing happened to me, I had a guy with explosives/mines in his backpack and I was setting them, I put a satchel charge down at my feet (was setting up an ambush), go to grab another and he accidently backed up so instead of opening his inventory i set off the bomb at my feet, the blast killed me and another 2 guys and wounded 4. BI Devs PLEASE fix this.

Some dampening to the removal of options would be nice. Graying them out but keeping them would be a good compromise to have responsiveness (fast use) and usability (predictable behavior) at the same time.

If options are added to the action menu (e.g. while moving toward a vehicle) the last selected menu point should remain selected (which it currently does).

Or scrap this whole thing and replace it with one or more "wheel"-like overlay interfaces that are extensible but always have the same actions at the same positions in the center of the screen. Selection by movement keys has some advantages too.