Hi,
acrylian, yes I was wrong to say "non working", I should have said not working as well as they did.
I've used a modified version of zpFocus for ages.
Things change and for those of you who code Zenphoto and the themes as a hobby I am grateful.
Back to the original question.
On my home server I change the max-width setting and the thumb size changes, also the size in the standard options changes.
All is fluid as it is designed as.
Quite amazing how as you change the browser window size the thumbs and layout changes.
Changing the thumb size in the themeoptions file doesn't do anything.
On my hosted server changing the max-width value still leaves me with 100px wide thumbs, the value is now set at 1200.
Altering the themes / default / themeoptions.php file
setThemeOptionDefault('thumb_size', 100); to 300 changes nothing.
Either viewing from the back end theme options page or the web page thumb size.
Weird.
Both Zenpage and zpBase are from the same .zip's on home and web servers.
I guess possibly a buggy install of Zenpage, but it seemed fine when I installed it.
I guess no big worry, will wait for the new Zenphoto version and zpBase and work out how I can break things from there

But would be nice to have the bigger thumbs ... 100px at current browser resolutions looks a tad strange.
As always all thoughts appreciated and will be tried.
Grahame