Trelby is a free word processing program to write screenplays. It is available for Windows and Linux, a version for Mac OS X is planned. Trelby is like, for example, Celtx is a free alternative to the program is Final Draft, Which the Anglo-American industry standard.
The program is simple. With a right-click can be made between different types of text (scene, action, After the completion of a script this can, for example, exported as a PDF file.
You can free download Trelby and safe install the latest trial or new full version for Windows 10 (x32, 64 bit) from the official site.