I find SciTE-st really fascinating (especially the ability to use multiple lexers in single file). I was just missing few features I was used to while working in Eclipse, like autocompleting function arguments or moving between placeholders using Tab key.

I modified the scripts a bit and added the following features:

1) Autocomplete on Ctrl+Space: the default SciTE (ctrl+enter) autocomplete si overriden by the "move to next line" operation, which I like and use, but I miss the autocomplete, so I adapted the example on http://lua-users.org/wiki/SciteAutoCompleteAnyLanguage and bound it to Ctrl+Space.

2) Autoinsertion of function arguments for Lua: you can set up Eclipse so that whenever you type '(' it automatically inserts appropriate arguments, and I adapted the idea for SciTE-st and Lua. I modified the scite.functions.show_args function so that it inserts the arguments directly into editor. It also sets the selection around the arguments, so that you can directly override them. It only looks for function definitions in the current file. It is bound to the '(' key, so it inserts the arguments directly while typing.

3) Modified key semantics during insertion of snippet: I haven't found a key sequence for moving to next item while inserting a snippet (i.e. while there are active placeholders). I decided to modify the code and added the following actions to keys while inserting a snippet:

• Tab: move to next placeholder, do mirroring/transformations
• Shift+Tab: move to previous placeholder
• Esc: cancel current snippet
• Enter: accept the snippet, skip any remaining placeholders (leave default value)
  

After the insertion is over (either accepted or canceled), the key bindings are returned to previous state. I find this more intuitive than existing solution.

If anyone is interested in these modifications, I uploaded the path to http://lua.pastebin.com/f79f8eabf .