The best editor is the one, which is set in $EDITOR of every unix user! So you need to make shortcut (same as in lynx) to start it for editing of <textarea> fields (or may be DblClick on field also will do this?). You just can't make own editor so powerfull as vi :) it whould be waste of time. Or may be it whould be defined by special option in preference? (if so - you hould also think about leting this external editor to get line number to start at and charset). So you could set "xterm -e 'vi $file' -fn '*-$charset'" (also tell user if $EDITOR is not set - especially for Win*) This need becomes clear, if you whould recall number of Web based Forums and Free Mail services. Most of them make <textarea> for 800x600 - too small for 1024x768 :(
See also bug 35268, [RFE] Edit Source using External Editor.
-->Future Maybe this bug should really go to HTML Form Controls or XPApps (for helper app work)?
Fun idea; it would actually make web mail usable. I don't expect we'll have the resources to do this any time soon, but it would be a nice self-contained project for someone to contribute. (Minor nit: $VISUAL, if it's set, should override $EDITOR.) It could be implemented as a form control issue (start editor on focus in) or as a key binding inside the editor. I'm leaving it as editor/core because if we built it in as an editor command it would also solve the much-requested comparable problem in mailnews. Not sure who should own it; Kin, if you don't want it, I don't mind having it on my list (but still future/helpwanted). If anyone wants to volunteer to work on it, I'd be happy to offer suggestions.
dup of bug 13474?
This one is a subset of bug #13474 And it is mor likely to be dup of bug #72539 But It could be implemented faster, then #13474 (with all proposed pipes) Maked as dependens (am I right?)
Mozex (firefox addon) currently supports choosing a hotkey to edit the textarea. Works for me with xemacs's winclient.exe using Firefox under Windows XP to edit trac wiki pages.