@Yzma approached me with this idea on the SHAR Crash Analyzer thread, so here it is.

What is it?

This is a text editor built specifically for MFK/CON scripts. The aim is to make modifying scripts a less-daunting task, as well as provide useful features that a standard text editor wouldn't.

Features

• Syntax Highlighting - Using a Lexer based off of the game's code itself, the editor applies Syntax Highlighting in real-time. This makes it easier to edit, and is nicer to look at than black on white.
• Functions Toolbox - Built into the application, but modifiable after first launch, is a list of every valid function from MFK and CON scripts, including Additional Script Functionality.
  
  • Sorted into categories. These can be refined after first launch by editing the settings.
  • Double clicking a function name will bring up a dialogue window with all the parameters (with names if known), as well as if they're required or not.
  • If a parameter has set/common values, there will be a drop-down box in the dialogue window.
  • Clicking OK in the dialogue window will insert the chosen function, with the entered parameters, into the current position in the current file.
• Script Validator - Runs the current file through the aforementioned Lexer, and returns and invalid tokens and their position if found. Will also return a warning if any function names are unknown.
• Templates - A template folder is created next to the settings file. Any files inside that folder will be loaded into a Template node in the Functions Toolbox. Double click a template to insert it into the current position in the current file.

How do I use it?

Download the below ZIP file, extract to a folder, and then double click the executable.

Download

EXE Virus Scan

Credits

• @Josh / Proddy - Main development.
• @Lucas Cardellini - Lexer assistance.
• @Yzma - Original idea.
• Special Thanks to everyone who helped map functions and their parameters.

Notes

• All functions are saved locally at %appdata%\SHARScriptHelper\Settings.xml, so you can modify them if you wish. (App must be closed to edit).
• Validate Script doesn't match things like AddObjective to a CloseObjective, only validates the formatting and known function names.
• Currently doesn't support Lua scripts written with game.lua.
• Any issues, questions or suggestions, let me know and I'll help where I can.

Thanks,
Josh

If anyone would like to build a template pack of useful snippets, I'm more than happy to link them in the main post.

Thanks,
Josh

v1.2 (Released 2021-02-18)

• Added the Close MFK functions. To load these you need to do Tools > Reset Functions Toolbox.
• Added a UI to manage functions.
• Added an additional Tool Strip with the commonly used menu items.
• Added Comment and Uncomment.
• Added the following symbols to the Syntax Highlighter: "(", ")", "{", "}", "," and ";".
• Added an Export As Game.Lua button to the File menu.
• Added Go To Line option to Go To.
• Made the text editor respect tab indentation.
• Removed New Line After Insert in place of it being a permanent addition.
• Added a prompt to update the function toolbox on the first launch of a new version.
• Edit Undo to work on a delay system, rather than on every character.

Apologies for the double release - too many bugs fixed to delay it though:
v1.3 (Released 2021-02-18)

• Fixed a bug where the text editor's right click menu never enabled the Cut/Copy/Delete buttons.
• Fixed a bug where previously opened files loaded after a file opened with the application.
• Fixed a bug where a directory was locked if application launched via a file.
• Fixed a bug where the line numbers didn't respect wrapped lines.
• Fixed a bug where inserting a function at the start of the file caused an unhandled exception.
• Fixed a bug where Redo didn't work since the Undo delay system change.
• Added block tab indentation.
• Added Shift + Tab support.
• Added global error handling.
• Improved Syntax Highlighting.

v1.4 (Released 2021-02-27)

• Added a check for argument length to the script validator. Now gives a warning if an argument is over 63 characters. If this is triggered, make sure to increase the argument in Custom Limits.
• Added a Validate Scripts in Directory button. Will run every .mfk and .con file through the verifier, and throw back any errors.
• Added the Filepath Helper. The aim of this is to assist with functions like LoadP3DFile.
  • Right click the Filepath Helper tab in order to add additional directories.
  • Your SHAR install will be included by default, pulled from the Mod Launcher.
  • For your mod, you should select the CustomFiles folder.
• Made the Function Manager Editor accept tabs and new lines in the text editor.
• Added Import/Export Functions.
• Added the new SetWheelieOffsetX ASF function.