Currently as item processing and item calc happens in linear way from the first item of
the list, if there is a show item in list it will be shown after a signicant
time interval only especially in case of big lists. This patch changes the item
calc order of the queue so that blocks will be assigned to items immediately
for all queued items but the item calc operation will be done starting from the show item.
This solution helps to show the show item immediately when genlist opens.
Signed-off-by: Godly T.Alias <email@example.com>