so that we can properly associate a widget with create, update, and
destroy events. Only used by Qt so far but it should be easy enough to
add to GTK+.
Rename ui/qt/progress_dialog.{h,cpp} to progress_bar.{h,cpp}. Show a
progress bar in the status bar of the main window instead of creating
a separate dialog. Note that we still need to add a "cancel" mechanism
and display the task and item titles somewhere.
Thus began the War Against Gratuitous Dialogs.
svn path=/trunk/; revision=43833