Fusion exhibits erratic behaviour when you attempt to activate components in the model tree. See screen cast.
While I guess the fade-in/out of the activation buttons is made for visual purposes, the less-than-ideally implemented feature breaks workflow efficiency.
I would wish for having the option of simply having the activation buttons always visible. Alternatively, fix it so the activation button always appears when the mouse hovers over.
I'm posting this in the idea-station since this "feature" has been there for ages, and i suspect it is not considered a bug.