feat(ui): let a widget opt out of the pressed style

A custom node that paints its own key highlight does not want the whole
node marked dirty on every press.

lua/lib/ui.lua

@@ -28,6 +28,7 @@ local ui = {}
 ---@field on_exit? UiHandler
 ---@field on_click? UiHandler
 ---@field paint? fun(id: NodeId, x: integer, y: integer, w: integer, h: integer)
+---@field press_style? boolean False for a widget that paints its own press feedback.
 
 ---@class UiConfirmSpec
 ---@field title string
@@ -49,6 +50,9 @@ local THEMES = {
 }
 
 local enterHandlers, exitHandlers, clickHandlers, painters = {}, {}, {}, {}
+-- A widget that paints its own press feedback opts out, so pressing one key does not
+-- repaint the whole node the way a pressed style would.
+local pressStyles = {}
 local laidOut = false
 local themeName
 local activeScreen
@@ -119,6 +123,7 @@ loadTheme(savedTheme and savedTheme:match("^%s*(.-)%s*$") or "light")
 
 local function clearState()
   enterHandlers, exitHandlers, clickHandlers, painters = {}, {}, {}, {}
+  pressStyles = {}
 end
 
 node.setPainter(function(id, x, y, w, h)
@@ -164,6 +169,7 @@ local function build(spec, kind)
   exitHandlers[id] = spec.on_exit
   clickHandlers[id] = spec.on_click
   painters[id] = spec.paint
+  pressStyles[id] = spec.press_style ~= false
   return id
 end
 
@@ -340,13 +346,13 @@ local function inside(id, x, y)
 end
 
 local function enter(id, x, y)
-  node.setPressed(id, true)
+  if pressStyles[id] then node.setPressed(id, true) end
   local handler = enterHandlers[id]
   if handler then handler(id, x, y) end
 end
 
 local function exit(id, x, y)
-  node.setPressed(id, false)
+  if pressStyles[id] then node.setPressed(id, false) end
   local handler = exitHandlers[id]
   if handler then handler(id, x, y) end
 end