1. When a popup calls up another popup,
A. isActive is cross-inherited (transferred) and will-not fire onactivate in the new popup ... (even though popup does not receive focus; and even though popup does not inherit isActive from its parent).
B. It momentarily throws itself to the new screen position, before displaying the new popup content.
2. When a popup is invoked, it also--
A. clears the clipboard, so that the browser cannot undo/redo;
B.
loses cursor-visibility, albeit its position is still there;
C.
defeats the mouse wheel, so that it cannot roll about the page
D.
on-escape hides the parent-cursor (or sets its 'thickness' to unshown; cf other thicknesses: thin, thick)
3. N.B. Use parent.method(), to access windows-dependent methods from a popup: e.g. with(parent) clearTimeout(timerN).
4. (2008-11-23) Buttons have gone intermittent, now-usually closing the popup onclick (without involving a timer).