myDevStudio as NSIS (Nullsoft Installer System) IDE
First of all download NSIS & install it. Ensure that makensis.exe in your PATH or setup with full path in Tools/File Types->NSIS : Compile|Buid|Run.
1st.
myDevStudio can edit NSIS-files with syntax highlight ( this can almost every editor )
and folding ( like VS.NET ! ).
myDevStudio editing NSIS-script:

2nd.
myDevStudio has intellisence: Word Complete & Parameters Info.
You can easily edit code - by selecting commands from list and
get parameters information with full description.
Word complete

Parameters info with description
3rd.
New Wizard: you can quickly create new NSIS-script.
First page

Second page
4th.
You can compile NSIS-script directly from myDevStudio and navigate on errors.
Build toolbar:

Output window with makensis.exe (NSIS-compiler) output: