The development environment is a tool designed to create, start, and test custom forms, units, and assemblies.
To open the Development Environment window, select the Tools > Development Environment item, or create an Assembly/Unit/Form/.Net Assembly in the object navigator.
If you select the Create > Form menu item, the development environment window shows an empty form without components:
The dialog box for creating a unit looks the same, but no form is available. Saving a form or unit for the first time shows a dialog box where you can specify a folder to save the form or unit to. When an assembly (.NET assembly) is created, it is saved to the repository object, from which the Create command was executed.