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/test/ui.lua

@@ -194,4 +194,24 @@ assert(columns == 3 and side == 93, "width is the binding constraint in portrait
 -- Five cards are two rows, so a reserve that eats the height budget shrinks the card.
 assert(select(1, ui.cardSide(5, 12, 8, 300)) == 74, "height binds once the reserve is large")
 
+-- A widget painting its own feedback is never given a pressed style, while an ordinary one
+-- still is. Which node was hit is geometry, so the test names the target directly.
+ui.reset()
+local pressedCalls = {}
+node.setPressed = function(_, on) pressedCalls[#pressedCalls + 1] = on end
+local own = ui.custom{h = 20, press_style = false, on_click = function() end}
+local styled = ui.button{h = 20, label = "ok", on_click = function() end}
+local board = ui.screen(ui.box{own, styled})
+local target
+node.hit = function() return target end
+
+target = own
+board:down(0, 0)
+board:up(0, 0)
+assert(#pressedCalls == 0, "a self-painting widget is not styled on press")
+
+target = styled
+board:down(0, 0)
+assert(pressedCalls[1] == true, "an ordinary widget still gets its pressed style")
+
 print("ok")