Time Recording +Summary +Interruptions. Now with accuracy to second. Set selected item as current by a single hotkey hit.  
 
 
Key folders
     Current (checkmark)
           no rules
     seconds (number)
           ++::0:
     SpentT (number)
           ++::0:
     SumT (number)
           ++:C!-:sumc(fv("SpentT"))+sumc(fv("SumT")):
     oldt (checkmark) - use it to find the just closed item, to correct SpentT manually if needed.
           no rules
 
 
Key LUAscript, used for offset time spent on a task:
 
function time()            
         
-- get time (mines a "zero level point" to fit into "number" folder type)          
local tnow = os.time()-1200000000          
         
-- new item (selected)          
itemnew = get_select_items()            
         
-- clear oldt
x = get_folder_items("oldt")  
max=table.maxn(x)  
for i=1,max do  
set_folder_value("oldt",x[i],0)  
end  
 
-- old item - calculate spent, unflag current, flag oldt
x = get_folder_items("Current")  
max=table.maxn(x)  
for i=1,max do  
spentjust = tnow - get_folder_value("seconds",x[i])  
msgbox(get_item_text(x[i]), "+" .. math.floor(spentjust/0.6)/100 .. " mins")
spentnew =  spentjust / 60 + get_folder_value("SpentT",x[i])
set_folder_value("SpentT",x[i],spentnew)  
set_folder_value("Current",x[i],0)  
set_folder_value("oldt",x[i],1)  
end
         
-- new item - flag current, unflag temp, renew seconds          
set_folder_value("Current",itemnew[1],1)            
set_folder_value("seconds",itemnew[1],tnow)          
         
end
 

Impressive!