I totally agree with @Mostapha about the reasons of using an external editor. I’ve been using Eclipse, but sometimes is “too much” to edit simple and small scripts and the built in editor is perhaps too simple and lacks options and refinement…and is ok, nobody is asking for a wonderful built-in editor (this implies maintenance, a design team, an add-ons platform…). A well connected external editor could bring awesome capabilities and improvements in workflow (plugins and addons, integration with other coding workflows…) and it will release Mcneel from the pressure of designing a wonderful integrated coding tool…you just need to design the connecting pipe 