new tags:
%vs(label, value) <- set variable named 'label' to integer 'value'
%vc(label) <- get the current value
%vt(label, timeout) <- has 'timeout' elapsed since variable 'label' changed values?



--------------------------------

%?vc(show_popup)<%Vd(popup)>

# popup viewport
%V(popup, .....)
%T(buttona, ...., action)
%?Tl(buttona, 1)<%vs(show_popup, 1)> 
%T(buttonb, ...., action)
%?Tl(buttonb, 1)<%vs(show_popup, 1)>
#and timeout to get rid of popup automagically
%?vt(show_popup, 15)<|%vs(show_popup, 0)>



# in some other viewport
%T(toggle, ...., none)
%?vc(show_popup)<%?Tl(toggle, 1)<%vs(show_popup, 1)>>