What is the point of display parameter in /authorize call of OIDC? Following is what spec says about OIDC parameter. However /authorize invocation is a redirection from client and whether a popup is opened by user-agent or user-agent changes URL on address bar is purely at client side. How /authorize endpoint will use "display" parameter?
display OPTIONAL. ASCII string value that specifies how the Authorization Server displays the authentication and consent user interface pages to the End-User. The defined values are:
page The Authorization Server SHOULD display the authentication and consent UI consistent with a full User Agent page view. If the display parameter is not specified, this is the default display mode.
popup The Authorization Server SHOULD display the authentication and consent UI consistent with a popup User Agent window. The popup User Agent window should be of an appropriate size for a login-focused dialog and should not obscure the entire window that it is popping up over.
touch The Authorization Server SHOULD display the authentication and consent UI consistent with a device that leverages a touch interface.
wap The Authorization Server SHOULD display the authentication and consent UI consistent with a "feature phone" type display. The Authorization Server MAY also attempt to detect the capabilities of the User Agent and present an appropriate display. If an OP receives a display value outside the set defined above that it does not understand, it MAY return an error or it MAY ignore it; in practice, not returning errors for not-understood values will help facilitate phasing in extensions using new display values.