I'm a bit stumped here: which GUI item sets the Envelope Control Panel name text colour? I tried the element finder, to no avail. In one theme I looked at, "Window text" changed it but in others (e.g. the Default theme) changing it has no effect.
Thank you - that would explain it - the problematic theme is unWaltered. I just added this line: set envcp.label.color [080 080 088] to the rtconfig.txt file in the theme