What I mean by the cryptic title is this: Let's say I have a dead actor. If the player clicks on it, he'll get to the inventory screen. I can script the OnActivate event but the usual behavior of the player clicking it will still occur, no matter what. Same with books or chairs or anything else that behaves by clicking.

Is there a way to disable the activation behavior when the player clicks on it?

you can use BlockActivation(), which will bypass the normal activation of your object. it will still run whatever OnActivate event you have in the script though

example, if you use BlockActivation on a container (it has to be called some time before the OnActivate event, such as OnCellAttach or OnInit). when the player activates it, it will make a "fail" sound effect, but still fire the Event OnActivate block of the script in its entirety without opening the inventory menu screen

Awesome! That is exactly what I need. Many thanks.

Basically what I did. I wanted a dead goat to be activatable, and display a message, without the inventory menu showing. So I attached a little BlockActivation script to it, then added another script calling the OnActivate message. Works brilliant

In your situation I recommend to call BlockActivation in an OnDeath Event.