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I have been trying to convince Adobe of this need since snippets were introduced. Please join my campaign.
The more people who report a bug or request a feature, the more likely it is to be actioned. Please follow this link.
See www.grainge.org for RoboHelp and Authoring tips
Snippets are non editable entities. When you click on the snippet used in a topic, the entire snippet gets selected. In your use case, if the first column contains lots of html elements ( like text, images etc), then you can create a snippet for those and insert that snippet in the first column. If you have only a single image (as you mentioned), then you can insert that image directly. I can't think of any other way.
Thank you Mr. Grainge. I think this feature, if Adobe implements, will prove to be very handy. I have joined the your campaign.
Yes, I'm doing that. However, I think the Editable Snippet feature will really be helpful. I hope Adobe implements this in their next version. Thank you!