Cross-domain communications between browser windows

A system, comprising:

• a first server that operates in a first domain and hosts a web page that provides functionality for performing a checkout transaction with a first entity when the web page is loaded in a first window, the web page configured to display a display element that is selectable by a user to initiate a payment transaction in support of the checkout transaction using an account with a second entity, the first window corresponding to the first domain;
• wherein the web page includes coding that creates an iframe in the first window, said iframe configured to receive content from a second server that operates in a second domain;
• wherein the coding of the web page is responsive to user selection of the display element by causing a second window to be displayed over a portion of the first window, wherein the second window displays content, including a log-in screen, that enables the user to interact with the second server and to log into the account with the second entity;
• wherein the iframe is configured to place a call to the first window in response to the user completing an interaction with the second server through the second window.

A first server that operates in a first domain and hosts an electronic page that includes functionality for a user to perform a checkout transaction with a first entity using an account of the user with a second entity, the page comprising:

• coding that causes an iframe to be created on the page when the page is loaded in a first window corresponding to the first domain;
• coding that causes the page to display a display element that is capable of being activated by the user when the page is loaded in the first window;
• and
• coding that is responsive to user activation of the display element by causing the page to display a second window that corresponds to a second domain, wherein the second window provides functionality, including a log-in screen, for the user to log into the account with the second entity by interacting with a second server in the second domain;
• wherein the iframe is configured to place a call to the first window in response to the user completing an interaction with the second server through the second window.

A non-transitory computer-readable medium that stores page coding that, when incorporated into a page hosted by a first server that operates in a first domain, provides functionality for a user to perform a transaction, the page coding comprising:

• coding configured to cause an iframe to be created on the page when the page is loaded in a first window corresponding to the first domain;
• coding configured to cause the page to display a display element that is capable of being activated by a user when the page is loaded in the first window;
• and
• coding that is responsive to user activation of the display element by causing the page to display a second window that corresponds to a second domain, wherein the second window provides functionality, including a log-in screen, for the user to log into an account by interacting with a second server in the second domain;
• wherein the iframe is configured to place a call to the first window in response to the user completing an interaction with the second server through the second window.