Flash Develop is a highly customizable, functional and very lightweight script editor, with advanced support for class-based programming languages. Although the Flash Develop editor has been designed primarily for ActionScript, other languages can also be easily implemented. It is written in open source, and therefore it is completely free. Its creators have put emphasis on getting a utility to program very light and fast, that allows to work even in old equipment.
Flash Develop is very fast and easy to configure. It is very simple in its management as an external editor and also as an open source development environment. It stands out for its ability to autocomplete and generate code. Other possibilities are, for example, the compilation and debugging of projects, exploration of SWf or SWC source files, a multitude of already included project templates, etc. We can also use Flash Develop as a full-fledged development environment, with functions such as lists of tasks or things to do, XML and HTML autocomplete, zen-coding for HTML ... as you see, we are facing a development tool more advanced
In short: if you are dedicated to programming with Flash, you should take a look at a tool like Flash Develop.
You can free download Flash Develop 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.