As documented in extension/ezoe/settings/content.ini.append.php:

## Will use custom image if there is a custom attribute on the tag named 'image_url'
#IsInline[externalimage]=image

However, this prevents you from having an inline, image-represented custom tag. Any attribute with this setting is placed on a new line after saving.

The problem is line 268 of kernel/classes/datatypes/ezxmltext/ezxmlschema.php

if ( $this->Schema['custom']['isInline'][$name] == 'true' )

Should be:

if ( (bool) $this->Schema['custom']['isInline'][$name] )

I know that this is technically a general eZP bug but it only manifests itself in functionality enabled by the Online Editor.

Steps to reproduce

1. Create a custom tag meant to display an image in the Online Editor with the IsInline[tag_name]=image
2. Insert the tag inline, and then store your draft.
3. The tag will be placed onto a new line.