I know how to add a Custom Experience (field) Button to a Rendering when it's directly added to a page inside a placeholder, however, I have a slightly different scenario.
I have a partial design that has a page content rendering with a variant selected. This gets used on the page design. So the content editor is adding a page using Experience Editor. I am not seeing how to add an experience editor button in this instance.
More specifically - I have an Article page, when it is being content edited in Experience Editor I need them to be able to click a button to modify 2 fields that make up the article template as they are not actually displayed on this page but belong with the content (eg. summary text field). Because the page content rendering is on the partial design - I don't get the usual buttons appearing at the top when on an individual page apart from field level.
I have an image as the first field - and so was thinking it would be good if I could add a custom button there. But even going to this field specifically and adding a custom experience button it is not appearing.
My rendering variant:
The partial design contains the Page Content rendering - which has the buttons I'm used to, but the page itself is going to be experience edited rather than the partial.
My rendering variant - responsive image - tied to the Banner Image field
UPDATE- strangely now I am seeing a disabled experience editor button in my image context menu. But I can't figure out why it is disabled - unless it's because it's getting confused about trying to edit teaser fields that are part of the parent article template.