Why have two ways (set/change) for element Alpha?

[mbb]

Curious, what's the point in having "set" Alpha and "change" Alpha? (or even set & change anything for that matter)

Why not just have one method and use it's "transition time" value to define how it changes? (ie: 0=set, $n=change)

[Hopki]

Many people still use older skins that did not have a time setting for the change alpha action.
I guess in time this will go.
Regards,
Hopki