FEATURE SUGESTION: layers

when you create a layer stack, it would be great to have a +/- on each layer.  and a drop down border that you can raise or lower. (+/-) so that when you put an effect on top of the stack you can extend its effect to all layers underneath, or limit its effect to one, two three, or whatever is directly under it.  SO for example you could apply LEVES adjustment to other underneath layers indivudually, instead of the entire stack. it would be great to specify levels, blur, dirt, a bunch of other filters to specify what they effect under them instead of them hitting EVERYTHING without discrimination. we also need some spline and selection based masking tools. hopefully this all makes sense. ive been using photoshop for 31 yrs, and i know substance is newish, but these tweaks would be fantastic please.