'center-window' — centered over the current browser window. Multi-monitor aware: the popup
follows whichever screen the browser window is on.
'default' — let the browser decide where to place the popup.
{ left, top } — explicit screen coordinates (relative to the top-left of the primary
screen, not the browser window), passed through to window.open.
Positioning is best-effort. The browser may clamp coordinates to keep the popup on-screen, and
some environments (notably Safari and mobile browsers) ignore positioning entirely.
Where the login popup should appear.
'center-window'— centered over the current browser window. Multi-monitor aware: the popup follows whichever screen the browser window is on.'default'— let the browser decide where to place the popup.{ left, top }— explicit screen coordinates (relative to the top-left of the primary screen, not the browser window), passed through towindow.open.Positioning is best-effort. The browser may clamp coordinates to keep the popup on-screen, and some environments (notably Safari and mobile browsers) ignore positioning entirely.