Re: Can't use 'Open page as structure' with "Neat" theme...
One difference between the Neat theme and most others is that it has its own tiki-show_page.tpl file (and also its own tiki-editpage.tpl and tiki.tpl files). I haven't looked at the files but suspect this may be what's causing the problem. Chances are these files haven't been updated in a long time and probably don't include code that's been added to the default template files needed for "open page as structure".
You could try renaming templates/styles/neat/tiki-show_page.tpl (to anything, just adding an "x" or something — it doesn't matter as long as the current name is changed so the file isn't found/used by Tiki) and seeing if the behavior you want is achieved when Tiki uses the default tiki-show_page.tpl file (in templates/) instead. Of course the styling of the page will change since Neat's variant isn't used anymore. If this styling is important, the Neat-specific tiki-show_page.tpl file will have to be edited/updated to get the code upgrades that the default file has.
It's also possible that the Neat CSS file is missing lines needed for the functionality, and if so the CSS selectors/properties involved in "open page as structure" will have to be identified (by checking a working theme) and added to neat.css.
If these things are done and the features still doesn't work, I don't really know what the problem would be.
-- Gary