This is a big one. Being able to create a tab/window to view custom data would be awesome, like a live HTML preview, OpenGL surface, graph rendered from an open data file, custom image format, etc.

I wouldn't mind the core ST app being so bare bones if the plugin API was more powerful, but unfortunately it is pretty limited in what you can do.

We've got quite a number of API enhancements in the next version, including HTML sheets for non-text content.

That said, we are definitely focused on being first and foremost a really fast text editor that makes it easy to read, navigate and write code. Trying to implement a browser or be an IDE are outside of our area of focus.