@joe: can fix this.
Committed.

Testing with debugging on I found I was getting a lot of these messages:

A non-numeric value encountered in file: C:\Users\Paul\htdocs\fa24\includes\ui\ui_controls.inc at line 258
C:\Users\Paul\htdocs\fa24\includes\ui\ui_view.inc:213:     viewer_link('Asset register','admin/view/view_package.php?id=asset_register','','','')
C:\Users\Paul\htdocs\fa24\admin\inst_module.php:121:     get_package_view_str('asset_register','Asset register')
C:\Users\Paul\htdocs\fa24\admin\inst_module.php:269:     display_extensions((Array[22]))

Problem was due to an extra '-' at the start of line 258 in  includes\ui\ui_controls.inc

-        $preview_str = "<a target='_blank' $class $id href='$path_to_root/$url' onclick=\"javascript:openWindow(this.href,this.target); return false;\"$pars[1]>$pars[0]</a>";

Removing the extra '-' fixed the issue

        $preview_str = "<a target='_blank' $class $id href='$path_to_root/$url' onclick=\"javascript:openWindow(this.href,this.target); return false;\"$pars[1]>$pars[0]</a>";

Hope this helps.