Toggling whitespace needs the panel beneath to render its diff again, which
is what HandleRenderToMain is for; HandleFocus does that and also everything
else that belongs to a panel gaining the focus, which this panel already has
or, when the focus is in the main view, does not want. Re-selecting its
current item is harmless, but re-deriving its highlight as a focused panel's
is not: the selection turns bright while the user is somewhere else.
Changing the context size and switching diff renderers already ask for a
re-render this way.
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
When toggling the value in the UI we simply overwrite the value in UserConfig;
this would be bad if there was ever a chance that we want to write the user
config back to disk, but it is very unlikely that we can do that, because
currently we have no way to tell which parts of the config come from the global
config file and which ones come from a repo-local one.
The option doesn't have any affect in these views, so we don't need to toggle it
here. But the problem was the HandleFocus call at the end: this would activate
the wrong view, so we need to avoid it here.
Show an error if the user tries to turn the option on, to let them know that it
doesn't work here.
