The following is a list of suggested external editors for editing FileMaker code.
Macintosh
TextMate can be used to gain the advantage of syntax highlighting, function expansion and other beneficial features. You will need both the core editor and the extension (known as a bundle) to gain the advantages. Each editor has a specific location where the extension needs to be located.
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On Macintosh, when using FileMaker 11 or greater, you can use the QuickCursor application to send any text within a FileMaker dialog box editing field to a designated editing application.
Windows
Notepad++ provides syntax highlighting and similar features to most other code editors. For FileMaker specific highlighting use the file provided by Dan Smith.
UltraEdit has long been a popular code editor on Windows. Providing support for many commonly requested features. No known syntax highlighting file for this editor as of yet.
Cross-Platform
Sublime Text 2 is a powerful cross-platform editor which has many extensions to empower the calculation writer. Many TextMate bundles will work with Sublime Text 2. (as of the last edit date on this page no testing has been done with regards to the FileMaker bundles listed above)
Calculation editing
The above listed editors, and their supported addons, modules or bundles (all different words to simply describe extensions of the core editors) are of little use when you consider that having to copy and paste calculation code is a manual process. The goal is to send the code from the FileMaker calculation dialog box into the editor where more power is offered. The following are methods for performing such a task.
Macintosh
When using FileMaker 11 or greater, you can use the QuickCursor application to send any text within a FileMaker dialog box editing field to a designated editing application. You can purchase this menu bar application from the App Store found under the Apple menu.