14. A computer implemented system of handling events generated by user interaction with a display that includes a first window and a second iframe that is not contained within the first window, the computer implemented system including: a processor, memory coupled to the processor, and program instructions stored in the memory that implement a method comprising: handling events generated by user interaction with a display that includes a first window and a second iframe that is not contained within the first window, including: generating a popup control of the first window responsive to a first user event representing user interaction with the first window; in circumstances when the user relocates a cursor from the first window to the second iframe and a focus event generated from a mouse or touch event within the second iframe is suppressed from propagation to the first window, receiving a blur event and a location of the blur event propagated from the second iframe, and responsive to the blur event in the second iframe, triggering a dismiss class within the first window, wherein the dismiss class dismisses at least a target portion of the generated popup control of the first window.
14. A computer implemented system of handling events generated by user interaction with a display that includes a first window and a second iframe that is not contained within the first window, the computer implemented system including: a processor, memory coupled to the processor, and program instructions stored in the memory that implement a method comprising: handling events generated by user interaction with a display that includes a first window and a second iframe that is not contained within the first window, including: generating a popup control of the first window responsive to a first user event representing user interaction with the first window; in circumstances when the user relocates a cursor from the first window to the second iframe and a focus event generated from a mouse or touch event within the second iframe is suppressed from propagation to the first window, receiving a blur event and a location of the blur event propagated from the second iframe, and responsive to the blur event in the second iframe, triggering a dismiss class within the first window, wherein the dismiss class dismisses at least a target portion of the generated popup control of the first window. 19. The system of claim 14 , further including: the second iframe being nested within a third iframe, the third iframe being nested within a common container of both the third iframe and the first window; and setting a curtain attribute of the third iframe to true, thereby causing propagation of a blur event from the third iframe to the common container.