15. A computer-readable storage device comprising computer program instructions for processing user manipulation of a set of input controls associated with an expansion control in a markup language document, the program instructions executable by one or more processors to perform actions including: a) receiving a notification that the expansion control is to be collapsed and in response detaching the set of input controls from a document object model (DOM) representing the markup language document; b) attaching the set of input controls to the DOM in response to a command to display at least a portion of the set of input controls; c) inserting a substitute control in the DOM and displaying the substitute control in response to the notification that the expansion control is to be collapsed, the command to display at least a portion of the set of input controls is invoked by a user selection of the substitute control; and d) storing a value of each input control of the set of input controls in a field of the DOM, the field remaining in the DOM after the set of input controls is detached from the DOM.
15. A computer-readable storage device comprising computer program instructions for processing user manipulation of a set of input controls associated with an expansion control in a markup language document, the program instructions executable by one or more processors to perform actions including: a) receiving a notification that the expansion control is to be collapsed and in response detaching the set of input controls from a document object model (DOM) representing the markup language document; b) attaching the set of input controls to the DOM in response to a command to display at least a portion of the set of input controls; c) inserting a substitute control in the DOM and displaying the substitute control in response to the notification that the expansion control is to be collapsed, the command to display at least a portion of the set of input controls is invoked by a user selection of the substitute control; and d) storing a value of each input control of the set of input controls in a field of the DOM, the field remaining in the DOM after the set of input controls is detached from the DOM. 18. The computer-readable storage device of claim 15 , wherein storing the value of each input control of the set of input controls is performed in response to receiving the notification that the expansion control is to be collapsed.