I'm currently trying to port TXModular to linux.

It's a modular software synth written in SuperCollider by Paul Miller.

Alas, it was not written with cross-platformness in mind.

Good news is that I already got most of the GUI working on linux.
Bad news is that I probably won't have the time to finish the port before traveling to South America so, to all charitable souls around, feel free to fork my github project and give a help.

I rewrote from scratch Completion plugin (formerly named auto-completion plugin) and added tons of neat features:

• new GUI (inspired from desire-data)
• added an option file
• auto-creation of completed objects (via Return key)
• added a 'save_mode' so pd remembers keywords for send/receive/table, etc..
• added a nearly-bash-completion mode
• completions update as you type
• etc...

Download the source code on github.

Pure-data 0.43 comes with the ability to write GUI plugins.
In order to propotype faster, I wrote this quick autocompletion plugin.

Grab the code on github.