Take the 2-minute tour ×  Cannot Align Semi-Transparent Items?
Windows Vista, Photoshop CS2.  Steps to repeat:    1. Create new
document   2. Fill a circle on a new layer   3. Drop opacity of
filled circle to 10%   4. Create new empty layer below circle
layer   5. Merge empty layer with filled circle layer   6.
Select entire canvas   7. Attempt to align layers to selection
layer > align layers to selection > vertical centers  I get the
following error:  Could not complete the Vertical Centers
command because there are no layers to be moved.  Clearly this
is not true, as I'm selecting the layer with the semi-
translucent ball on it. Now, if you had tried this same command
prior to step 5 (when the layer was at 10% opacity) it would
have worked.  Is there some way around this problem? I need to
move layers around that begin as transparent items, with a layer
opacity at 100% where 100% of the layers opacity results in
showing objects that are themselves not-very opaque.  I've
confirmed on another machine tha