9. A tangible non-transitory computer readable storage medium holding code that, when executed, causes a computer system to: receive an input selecting among at least menu, auto complete, date picker, and dialog popup controls to generate code for the selected popup control; generate code for completion of the selected menu, auto complete, date picker, and dialog popup control, wherein the generated code extends base popup code to implement the selected popup control, interacts with a controller-and-view interface and further includes: at least one popup control implemented by a base popup container that includes a trigger component and a target component that interact with a controller-and-view interface to respond to transition events that cause the popup control to collapse, expand, show, and hide the popup control, and to recognize a trigger-select; wherein generating code for the dialog popup control includes generating markup that causes a browser to use supplemental accessibility information in the markup to enable people with a visual impairment to perceive web content, wherein the supplemental accessibility information includes a text alternative for non-text content; the trigger component, when invoked, causes the controller-and-view interface to invoke the target component; and the target component, when invoked, reveals and enumerates selectable target actions; and interact with a user to edit the generated code, including accepting user inputs to complete the base popup container, the trigger component and the target component and implement a completed popup control corresponding to the user selection; and store the completed popup control for later use.
9. A tangible non-transitory computer readable storage medium holding code that, when executed, causes a computer system to: receive an input selecting among at least menu, auto complete, date picker, and dialog popup controls to generate code for the selected popup control; generate code for completion of the selected menu, auto complete, date picker, and dialog popup control, wherein the generated code extends base popup code to implement the selected popup control, interacts with a controller-and-view interface and further includes: at least one popup control implemented by a base popup container that includes a trigger component and a target component that interact with a controller-and-view interface to respond to transition events that cause the popup control to collapse, expand, show, and hide the popup control, and to recognize a trigger-select; wherein generating code for the dialog popup control includes generating markup that causes a browser to use supplemental accessibility information in the markup to enable people with a visual impairment to perceive web content, wherein the supplemental accessibility information includes a text alternative for non-text content; the trigger component, when invoked, causes the controller-and-view interface to invoke the target component; and the target component, when invoked, reveals and enumerates selectable target actions; and interact with a user to edit the generated code, including accepting user inputs to complete the base popup container, the trigger component and the target component and implement a completed popup control corresponding to the user selection; and store the completed popup control for later use. 11. The tangible non-transitory computer readable storage medium of claim 9 , wherein generating the target component further includes generating a positioning attribute that selects between automatic and manual positioning of the target component and enables reporting to accessibility technologies of a position at which the target component will be displayed.