I was able to get the effect you are after, I think, by increasing the frame's bottom inset by the amount of "underhang" on the image.
Well, the issue is, I won't know either the height of the image, or the length of description text. These are both dynamically loaded from a data source. Am I right in thinking I can't create a container which contains a text frame and an image frame?
Many thanks to Peter for his reply, but can anyone answer the question of whether its possible in inDesign to create a container which contains a text frame and an image frame?
I think you may have also misunderstood the initial question Peter, I am trying to remove the area indicated with the red arrows, not create it. :-)
Sorry, been out for an hour.
I understood that you want to have some variable height text frame (the gray box), and that this box should reduce in height to fit the text contained therein, but not less than necessary for the bottom to be 2mm below the bottom edge of the variable height image (which I'm presuming is anchored to the first line of text in the frame) in a case where there is not sufficient text for fit frame to content to avoide making the frame shorter than the bottom of the image.
I believe this could be scripted, but that will still require you to run the script. You should ask over in InDesign Scripting
As far as a container that holds both text and image frames, yes, but only if you "paste into" a new frame after creating the two separately and grouping, which probably is not what you have in mind.
Tough one... sounds like a job for a dedicated VDP plugin/standalone program which will let you set rules on all the content. You will also need a rule to push the lower text down as the image grows.
Maybe one of these will do it?
Easy to do with Pageflex Persona, but this is a horrible design program (a la Quark 3) with poor support, so probably not recommended!