You can use OpenSCAD with almost any external text editor, here is the short explanation:
OpenScad is able to check for changes of files and automatically recompile if a file change occurs. To use this feature enable "Design->Automatic Reload and Compile"
Once the feature is activated, just load the scad file within OpenSCAD as usual ("File->Open..").
After that, open the scad file in your favorite editor too. Edit and work on the scad file within the external editor. Whenever the file is saved to disk (from within the external editor), OpenSCAD will recognize the file change and automatically recompiles accordingly.
The internal editor can be hidden by minimizing the frame with the mouse or by selecting "View->Hide editor".Open SCAD is programmatic CAD that is used most often, but there are many others. Some of them have syntax coloring, and probably some more could be used with external text editors.
Textmate (Mac OS only) OpenSCAD add-on:
Textmate webpage: http://macromates.com/
Notepad++ language file:
Notepad++ text editor download: http://notepad-plus-plus.org/
Sublime Text 2 OpenSCAD add-on:http://www.thingiverse.com/thing:235558
Sublime Text multiplatfrom text editor: http://www.sublimetext.com/
Here are some information how to use OpenSCAD with
and Kate: here is the Kate syntax file http://www.thingiverse.com/thing:29505