Just wondering......(if anyone can help clear this up for me...)
what is the difference (if any) between the:
1) Opacity % box (on the bottom tool bar)& the
2) Alpha (Opacity) slider setting. ( in the fill & Stroke properties window)

I.E. are these just 2 different ways to do the same thing? Or do they have slightly different functions?.

The reason i ask is that changing one does not update the other and they seem to conflict with each other....

Is this just a bug or is there some explanation for this?

It must be a bug, the other one updates when you change one.

Are you sure you're looking at opacity slider, and not A box (alpha), because that box only changes opacity of fill or stroke (independently)?

The opacity box on the toolbar is the same as the object opacity slider at the bottom of the fill/stroke dialog, and is the whole object opacity. (and is linked)
The alpha (opacity) slider that your refering to is the alpha part of the color thats being applied to the stroke or fill, and is specific to either the fill or stroke style.

So you can create opaque colours......Ok
And then use these in objects and object groupings and still have the ability to apply the general object opacity to the group as a whole......
This is the reason?
It makes sense i guess....
Thanks for that......

Thats exactly it.

There is also a nice feature that you can make fill transparent and stroke opaque when you're using A box, when using the opacity slider it is applied to the whole object, fill and stroke.

There is a conflict between Opacity and Alpha, and the last time I saw it discussed it was intentional.

Inkscape gives the impression that colour is made up of RGBA, but it's not. In SVG there is only RGB, with an Opacity. Opacity can be applied to the fill, stroke, gradient stop or an entire object. [Please correct me if I'm wrong].

Typically Inkscape treats A as a colour value and O as the overall objects transparency. But the line get blurred and difficult to understand with gradient stops. If you have a 50% transparent stop, the opacity value will be 50% and the alpha value will be 255. If you move the alpha value it effects the opacity value as well as the Alpha. If you deselect the stop then select it again, the alpha will return to 255 and opacity will be the set to the new value. So this is the one situation opacity does not apply to an entire object, and instead applies to the fill.

To me, even though everything uses opacity in the SVG code, I think concepts of Alpha should be reserved for when we are dealing with colour (fill, stroke, gradient) and opacity should apply to the overall object.

Just when i thought i had wrapped my head around that one....
I'll have to re-read that a few times...(thanks for the info though)