Added progress dialog for downloads

Where are we going, Walt Whitman? The doors close in a hour. Which way
does your beard point tonight? (I touch your book and dream of our
odyssey in the supermarket and feel absurd.) Will we walk all night
through solitary streets? The trees add shade to shade, lights out in
the houses, we'll both be lonely. Will we stroll dreaming of the lost
America of love past blue automo- biles in driveways, home to our silent
cottage? Ah, dear father, graybeard, lonely old courage-teacher, what
America did you have when Charon quit poling his ferry and you got out
on a smoking bank and stood watching the boat disappear on the black
waters of Lethe?