Acme is a text editor/programming environment written for the Plan 9 operating system (see PlanNineFromBellLabs). It takes a substantially different tack than other windowing environments. Among its interesting properties are:
RussCox? (and friends) has ported much of the Plan 9 user-space to Unix-like systems. His plan9port package (PlanNineFromUserSpace) includes acme. See the home page at http://swtch.com/plan9port/.
The InfernoOs version of acme has been packaged with some extra goodies (wiki editor, irc client, etc) as a standalone program that can run on Windows, Linux and OS X under the name AcmeStandAloneComplex?: http://code.google.com/p/acme-sac/
GaryCapell (and friends) has written an acme imitation for Unix called wily. There's a home page at http://www.cs.yorku.ca/~oz/wily/index.html but wily is mostly deprecated in favor of p9p/acme and acme-sac mentioned earlier.
The IonWindowManager organises ordinary managed windows in a similar fashion to Acme. The Wily page above mentions that using the window manager for, er, managing windows might be tidier. Is this a call for a window-spawning text editor with Acme's style of shell integration? Not sure. Will it work under screen(1)?
Sounds like oberon-v4 to me but i never got that far to use it as a crossplatform ide (emacs replacement). see http://www.oberon.ethz.ch
-- EngelBert?