Main screen:

   For all views, all modes:

      Mouse click header - nothing happens.

      Mouse click on ProcessTable title bar - exit Tree view, update FunctionBar, title bar updates, sort by clicked field.
*** FAILING: wrong FB update depending on mode; does not change sort in wip branch
         click on same entry - invert sort.
            click on another entry - sort another field.

      Mouse click on a process - select that process.

      for each entry in FunctionBar:
         Mouse click entry - perform action of associated key.

   In Normal mode, Sorted view:

      <+> or <-> - do nothing.

      <F6> - enter SortBy screen.

   In Normal mode, Tree view:

      select process - update F6 in FunctionBar if subtree is collapsed or expanded.

      <F6>, <+> or <-> - expand/collapse subtree.

   In Normal mode, either Sorted or Tree view:

      <F3>, </> - activate Search mode.

      <F4>, <\> - activate Filter mode.

      <F7>, <]> - as root only, decrease process NICE value.

      <F8>, <[> - increase process NICE value.

      <a> - enter Affinity screen.

      <b> - do nothing.

      <c> - select process and all its children.

      <d>, <e>, <f>, <g> - do nothing.

      <F1>, <h>, <?> - enter Help screen.

      <i> - on Linux, enter IOPriority screen.

      <j> - do nothing.

      <F9>, <k> - enter Kill screen.

      <l> - enter LSOF screen.

      <m>, <n>, <o> - do nothing.

      <p> - hide/show program path.

      <F10>, <q> - quit program.

      <r> - do nothing.

      <s> - enter STrace screen.

      <F5>, <t> - toggle between Tree and Sorted view, update F5 in FunctionBar, follow process

      <u> - enter User screen.

      <v>, <w>, <x>, <y>, <z> - do nothing.

      <A>, <B> - do nothing.

      <F2>, <C>, <S> - enter Setup screen.

      <D>, <E> - do nothing.

      <F> - follow process.

      <G> - do nothing.

      <H> - toggle show/hide userland threads.

      <I> - invert sort order.

      <J> - do nothing.

      <K> - toggle show/hide kernel threads.

      <L> - do nothing.

      <M> - enter Sorted view, update function bar, sort by MEM%.

      <N>, <O> - do nothing.

      <P> - enter Sorted view, update function bar, sort by CPU%.

      <Q>, <R> - do nothing.

      <T> - enter Sorted view, update function bar, sort by TIME.

      <U> - untag all processes.

      <V>, <W>, <X>, <Y>, <Z> - do nothing.

      <<>, <>>, <,>, <.> - enter SortBy screen.

      space - tag current process, move down cursor.

      numbers - incremental PID search.

   In Search mode:

      TODO

   In Filter mode:

      TODO

Setup screen:

   TODO

SortBy screen:

   TODO

User screen:

   TODO

Kill screen:

   TODO

Affinity screen:

   TODO

Help screen:

   any key - back to Main screen.

IOPriority screen:

   TODO

STrace screen:

   TODO

LSOF screen:

   TODO