focus.txt

--devel-focus
	Window->focus
	need Window->operation()

on Dialog.run(), main loop could compile array of event "receivers"
	recursive descent of Window tree
	start at focus, breadth-first search

focus on Pager: focus list is
- Pager
- Index
- Sidebar
- CmdWin
- NeoMutt

PBar, IBar, HelpBar, containers are passive

CmdWin handles ":"!
Sidebar manages its own commands, uses dlg functions to change state
Index controls whether Pager is visible - Next Email, etc
Pager handles 'q', hides self, restores focus to Index
NeoMutt handles 'V' version and other globals
CmdWin: <what-key>

NeoMutt catches ":" unless overridden by the Dialog
	e.g. a backgrounded compose

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define functions to move focus between windows
	<focus-left>
	<focus-right>
	<focus-up>
	<focus-down>

the primary window will still need to run the event loop
	index: op = km_dokey(MENU_MAIN);
	pager: ch = km_dokey(MENU_PAGER);

need functions to navigate between sibling windows

index <--> sidebar

sidebar
	Generic          -> Sidebar
	<next-entry>     -> <sidebar-next>
	<previous-entry> -> <sidebar-prev>
	<select-entry>   -> <sidebar-open>

how is the focus shown to the user?
	background colour?
	dimming other windows?
	terminal cursor
	extra colour for hightlight/selection?
	on loss of focus:
		selection becomes highlight-coloured
		highlight loses colour
	on gaining focus
		selection regains selection colour
		highlight regains highlight colour

Events handled by Window.event()
	requires wdata
	separation of calc/paint useful too