1. In a computing system that includes an integrated development environment configured to receive user input for developing computing programs, a method for utilizing one or more code builders within the integrated development environment to generate customized code in response to the user input, the method comprising: providing an integrated development environment including a plurality of code builders configured to generate code for a coded program in any of multiple code languages and in one or more markup languages by applying user input to corresponding code document object models, wherein the integrated development environment further includes: a toolbox including a plurality of previously defined code builders; a programming frame, wherein the programming frame includes a plurality of alternate display views for displaying program code comprising both source code and markup language code, the alternate display views including at least a visual design view, a markup language view, a code view, and a combined view, the code view displaying source code and having a plurality of lines for source code at which source code generated by the code builders can be placed, and the combined view displaying source code mixed with markup language, and wherein displaying the markup language view comprises running a separation algorithm on the existing program, wherein running the separation algorithm includes creating a WebForms document that contains an in-memory representation of the existing program in the form of a text buffer, the WebForms document containing the separation algorithm which is run and extracts source code and markup from the existing program and maintains each separately; and an information view identifying properties associated with source code in the code view; wherein each of the toolbox, programming frame, and information view are displayed simultaneously, in a common window of the integrated development environment; receiving user input selecting one of the plurality of previously defined code builders included in the toolbox; in the code view, receiving user input selecting one of the plurality of lines for source code to identify a desired location in the code view for insertion of source code generated by the selected code builder; automatically, and in response to receiving user input selecting one of the plurality of lines as the desired location for insertion of source code generated by the selected previously defined code builder within the coded program, and before inserting customized source code at the selected one of the plurality of lines, displaying a code builder interface that overlays the common window and which prompts a user for customized input that will be used to determine at least in part the code that is generated by the code builder; receiving the customized input from the user; applying the customized input to the corresponding document object model to dynamically generate customized source code after receipt of the user input selecting one of the plurality of lines for insertion of the source code; and inserting the customized source code at the desired location within the code view of the integrated development environment.