To solve this question, the user needs to understand the purpose of a code editor and its role in programming.

A code editor is a software application or a part of an integrated development environment (IDE) that allows programmers to write and edit source code. It provides a user-friendly interface for writing, modifying, and organizing code.

Now, let's go through each option and explain what it represents:

A. Adding forms to the project: This option is not accomplished in the code editor. Adding forms to a project typically involves using a visual interface or design view to create and customize forms.

B. Adding controls to the form: This option is accomplished in the code editor. Once a form is created, the programmer can use the code editor to add controls (such as buttons, textboxes, etc.) to the form and specify their properties and behaviors through code.

C. Adding event procedures to the form: This option is accomplished in the code editor. Event procedures define the code that should be executed when a specific event occurs, such as a button click or a form load. The programmer can write and edit these event procedures in the code editor.

D. Both a and b: This option is incorrect. Adding forms to a project is not accomplished in the code editor.

E. All of the above: This option is incorrect. Adding forms to a project is not accomplished in the code editor.

Based on the explanations above, the correct answer is:

C. Adding event procedures to the form.