I confirm that compiling from source with libgnomeui-dev is the correct fix for this: The package in repository should be recompiled with dependency on libgnomeui-dev.
I took a quick glance at the jack-rack code and the it seems that the problem is probably not explicitly in the jack-rack. The open and save dialogs used in the code are GtkFileChooserDialogs, so I'd guess that the Ubuntu version of GtkFileChooserDialog is dependent on libgnomeui...
I confirm that compiling from source with libgnomeui-dev is the correct fix for this: The package in repository should be recompiled with dependency on libgnomeui-dev.
I took a quick glance at the jack-rack code and the it seems that the problem is probably not explicitly in the jack-rack. The open and save dialogs used in the code are GtkFileChooserD ialogs, so I'd guess that the Ubuntu version of GtkFileChooserD ialog is dependent on libgnomeui...