@subsection Popup

@deftp {Web Component for VEvent} PopupElement
@wcindex <popup-element>
@wcindex popup-element
@code{<popup-element>}

A (small) floating window containing information, which can be dragged
arround. Consists of a navigation bar with a few buttons for
controlling the window, which also works as a drag handle, along with
an area for contents, which can be resized by the user.

Currently tightly coupled to VEvent's, since their color
profile is derived from their owning events calendar, and they have
action buttons for the event in their navigation bar.

@deftypecv {Static Member} PopupElement {PopupElement?} activePopup
The popup which was most recently interacted with by the user. Used to
move it on top of all others, as well as sending relevant key events there.
@end deftypecv

@defcv {Attribute} PopupElement visible
Present is the popup is currently visible, absent otherwise.
@end defcv

@deftypeivar PopupElement boolean visible
See the attribute of the same name.
@end deftypeivar

@defmethod PopupElement maximize
Resize the popup window to fill the current viewport (mostly). Is
probably bonud to the maximize button in the navigation bar.
@end defmethod
@end deftp

@deftypefun PopupElement setup_popup_element VEvent
Create a new popup element for the given VEvent, and ready it for
editing the event. Used when creating event (through the frontend).
The return value can safely be ignored.
@end deftypefun