I feel that this "transparency-opacity" slider would be great because not everyone is skilled at creating filters or even editing current filters (like me). This would be great for future Filter Forge buyers who might be intimidated by the Filter Editor when first starting out (like me).
Plus, if no one has an objection, I feel this "Effect Slider" would be really helpful if placed on the settings tab at the bottom, unless someone could think of a more intuitive place to put it.
Maybe, someone will hear my wish. Oh, I WISH I WISH I WISH for a "transparency-opacity" slider (anybody got a golden Aladdin's lamp we could rub?)!

"Art really can have a purpose."