Retain original, unexpanded art for pattern swatches.
"This pattern contains active content (symbols, effects, etc, it's a long list) that must be expanded to create a swatch. If you edit the pattern again, the expanded content will no longer be active."
There's a lot of clever, well-paid people at Adobe. I bet someone there can figure out how to store the original pattern art along with the expanded pattern art, and edit the former rather than the latter when I double-click on the pattern swatch. I have workarounds for this but they are tedious and annoying ones.
Also I would like to thank whoever wrote the dialogue text I quoted, it would have been so easy to just say that the pattern contains Forbidden Art and leave me to figure out exactly what triggers the warning.
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A related request:
Edit a Brush like a Symbol, on canvas
http://illustrator.uservoice.com/forums/333657/suggestions/44725501 -
Oh, I’d love to have it. The way all my effects get expanded within a pattern tile just sucks. I am forced to keep the originals on canvas and constantly update swatches.