Szymon,
Sometimes working with Dialogs in Monkeybars can be a little odd because of the modal effects and how it blocks the current thread, which can keep Monkeybars from registering handlers properly.

Here's some code I've been using:

# in the dialog controller. This allows you to listen for when the dialog is closed
add_listener :type => :window, :components => [:java_window]

# here's the code in the controller that consumes it
DestinationSelectionController.define_handler( :window_closed ) do |event|
  update_view
end

Some other code I have isn't as nice. It's been a while since I've used this code, but I believe this is done because the dialog is modal.

# the view of the dialog
# the dialog is created manually here. This is in an MDI app, so it's fairly reasonable to know how to get to the view and grab it's main view component.
def create_main_view_component
  ShareGroupProgressDialog.new(mdi_view.instance_variable_get(:@main_view_component), true)
end

# to consume the respective controller:
ShareGroupProgressController.instance.open

I hope that gives you a start. Let me know if you have more questions!