How can i change values in a different built-in messages.properties,
like a messages.propertiesin org.eclipse.ui.internal.views.properties ?
You can provide a fragment with a translation of message.properties
(like the NL packs that eclipse.org provides). You then pick the new
locale and away you go.
Or you mean you just want to change a couple of values in the english
version shipped with eclipse? That you can't really do.