Hi Dean, great plugin, but I am wondering why you doubled the thumbnail size in the last release
You used to have
add_image_size('photospace_responsive_thumbnails', $options['thumbnail_width'], $options['thumbnail_height'], $options['thumbnail_crop']);
and now have
add_image_size('photospace_responsive_thumbnails', $options['thumbnail_width'] * 2, $options['thumbnail_height'] * 2, $options['thumbnail_crop']);
At first I thought it was something I had done wrong, regenerated thumbnails etc. But it is code related.
I was wondering if there was a specific reason why?
Also, can you please change line 145 to
add_submenu_page( 'options-general.php', 'Photospace Responsive options', 'Photospace Responsive', 'edit_theme_options', basename(__FILE__), array('photospace_responsive_plugin_options', 'display'));
As for sites where for security reasons 'edit_theme' (your current capability) is turned off to disallow editing the php files, the menu option doesn't appear. I suggest edit_theme_options is a more appropriate capability.