David I believe this has being done before. Search for sidebar editor.
However we could build one. Or a special tiddler containing two tiddlers with separate modes. Tony -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/c9fbdc4a-bf50-4ccf-9a1e-126cd2c5bb9f%40googlegroups.com.

