the screen, toolbar and slit rc values are reloaded in BScreen::reconfigure() before the menus.
the toolbar and slit rc values are explicitly loaded in their constructors, as is BScreen's.
on start, the config file is read entirely off the disc, and missing values are assigned defaults.
the config file is immediately written back to the disk to populate missing defaults in the file.
any time a config option is changed the control, the config file is re-written with the change.
choosing reconfig will reload the current config file on the disc.
on shutdown, nothing is written to the config file.
