Currently macro context creation is hidden in a private method in Macros.scala: https://github.com/scala/scala/blob/6858d9a2fffd7e85144e16a5e636c2b1c95c2b3a/src/compiler/scala/tools/nsc/typechecker/Macros.scala#L553.

After discussing type macros during the company meeting in Lausanne, we came to the conclusion that we need to make this method overridable, so that the interactive global could create its own context with front end facilities overriden to leverage the UI of the IDE.