To support interoperability between designer tools and FX runtime there should be InnerGlow and OuterGlow effects. They are similar to InnerShadow and DropShadow effects, the difference is they are not movable (there is no offsetX/Y attribute) and the actual effect fades quickly away (see attached image). The effect should have also "strength" attribute, which allows to specify how strong the glow effect is.

Another possiblity is to add the above functionality to DropShadow and InnerShadow effects - this would require addition of strength attribute and ability to specify a type of the fading away algorithm (I suppose we could have glow/shadow type).