I tested external resolution a long time ago when I first started and couldn't find any differences. Testing again today still finds no changes.
There are a few issues here, the first being that resolving the table dependency is very difficult for the app to do on its own (is this a draft DSDT?, is it for a different machine?, should it use the system SSDT or the one that was just created and not yet saved?, etc). This is already complex when trying to handle both Chimera and Clover injection (Clover support coming in beta #3), and might be impossible if trying to resolve an SSDT as well. Most document-based apps are meant to have their documents stand alone, without dependencies, and asking the user for each compile, or trying to work up some kind of dependency expression would make it too complex and error-prone.
The second issue is that while SSDTs themselves are content-agnostic (they can contain any kind of addendum necessary for the DSDT), Apple uses its SSDT in a very specific way (for CPU power management), which makes the possibility of an issue rarer. So long as DSDTs and SSDTs made for OSX have this well-defined layout, the most that is necessary in some cases is DropSSDT=Yes in Chimera.
Finally, if you are afraid of an issue extract your DSDT and SSDT, then decompile once `iasl -d DSDT.aml` and again `iasl -e SSDT.aml -p DSDT1 -d DSDT.aml`, then `diff -u DSDT.dsl DSDT1.dsl` and see if you find any differences besides the header.
I have added code folding as a TODO, but that will probably take a long time. I have avoided any solutions which required actually drawing onscreen because of the possibility for memory and drawing errors, in fact you may have noticed that the line numbering is really just a ruler with the correct scale. This is because the ruler is a feature provided by Cocoa which doesn't require writing your own drawing method; the drawing, memory management, and releasing are all handled by the framework, and even then it draws incorrectly from time to time. I doubt my subclass would perform as well or with the same amount of memory. Staying away from CG drawing keeps the number of possible issues low, and lets me focus on the mechanics of features, not appearance.