allow buttons to nest as well

button.lua

@@ -1,6 +1,11 @@
 -- Simple immediate-mode buttons with (currently) just an onpress1 handler for
 -- the left button.
--- If any applicable button handler returns true, it'll propagate the click to other handlers.
+--
+-- Buttons can nest in principle, though I haven't actually used that yet.
+--
+-- Don't rely on the order in which handlers are run. Within any widget, all
+-- applicable button handlers will run. If _any_ of them returns true, the
+-- event will continue to propagate elsewhere in the widget.
 
 -- draw button and queue up event handlers
 function button(State, name, params)
@@ -18,11 +23,15 @@ function mouse_press_consumed_by_any_button_handler(State, x, y, mouse_button)
   if State.button_handlers == nil then
     return
   end
+  local result = false
   for _,ev in ipairs(State.button_handlers) do
     if x>ev.x and x<ev.x+ev.w and y>ev.y and y<ev.y+ev.h then
       if ev.onpress1 and mouse_button == 1 then
-        return not ev.onpress1()
+        if not ev.onpress1() then
+          result = true
+        end
       end
     end
   end
+  return result
 end