If you want to contribute to the core code, you must follow our contribution policy.
This topic explains how to prepare your patch.
Before writing a patch, please, familiarize yourself with our Coding Style conventions.
You can create a patch using "Create Patch" SVN command.
If you are using Subversive plugin you can use the following steps:
Once the patch is created you should register the functionality provided with our Jira tracking system by creating new issue, submitting the description, patch and test case if applicable.