We try to split the code that touches debconf from the UI code as much as possible. In the case of plugins such as ubi-prepare, code that reads from debconf should be located in the Page class, under the prepare function in your case. That should then call self.ui.some_function_to_set_the_ui_appropriately, making sure to either implement it in an interface-neutral way, or account for the KDE frontend either by implementing a function in PageKde as well as PageGtk, or by stubbing out a default function in PageBase or PageKde.
Jonathan,
We try to split the code that touches debconf from the UI code as much as possible. In the case of plugins such as ubi-prepare, code that reads from debconf should be located in the Page class, under the prepare function in your case. That should then call self.ui. some_function_ to_set_ the_ui_ appropriately, making sure to either implement it in an interface-neutral way, or account for the KDE frontend either by implementing a function in PageKde as well as PageGtk, or by stubbing out a default function in PageBase or PageKde.
Hope that helps!