Description of your request or bug report:
Every time I see the (x) icon I can’t help but think there’s a better icon for this. When it’s used for deleting something it should probably be a trash can instead, but in the case of hiding activity it’s not actually deleting anything. For that reason, I propose changing the (x) icon with the eye with a slash icon.
I can’t figure out how to adjust the HTML to show it in context, but I’m referring to this icon:
EDIT: Also, if there’s anywhere that shows already hidden activity and allows the activity to be unhidden, you could use the regular eye icon for that.