Would like to build a GUI designer/builder for custom file type. A user would draw their components and the plugin would build the associated declarative language, which would then eventually feed into a build step. I'm new to plugin development. Looking to see if either the IntelliJ GUI builder code is open source or if anyone can point to examples or documentation to:
Create the skeleton or hooks to a graphic file editor as opposed to a text editor and associate it with a file extension, such '.gtemplate'.
Add toolbar icons/actions that only appear when new graphic editor plugin is in use.
Add support to create new graphic template file in standard Java project.