Reset bgimg style when centering labels

README.md

@@ -138,6 +138,7 @@ These utilities likely aren't compatible with flow.
  - [Just_Visiting's formspec editor](https://content.minetest.net/packages/Just_Visiting/formspec_editor) is a Minetest (sub)game that lets you edit formspecs and preview them as you go
  - [kuto](https://github.com/TerraQuest-Studios/kuto/) is a formspec library that has some extra widgets/components and has a callback API. Some automatic sizing can be done for buttons.
    - It may be possible to use kuto's components with flow somehow as they both use formspec_ast internally.
+   - kuto was the the source of the "on_event" function idea.
  - [My web-based formspec editor](https://forum.minetest.net/viewtopic.php?f=14&t=24130) lets you add elements and drag+drop them, however it doesn't support all formspec features.
 
 ## Elements

init.lua

@@ -309,29 +309,51 @@ function align_types.fill(node, x, w, extra_space)
 
         -- Hack
         node.type = "container"
+
+        -- Reset bgimg, some games apply styling to all image_buttons inside
+        -- the formspec prepend
         node[1] = {
+            type = "style",
+            -- MT 5.1.0 only supports one style selector
+            selectors = {"\1"},
+
+            -- bgimg_pressed is included for 5.1.0 support
+            -- bgimg_hovered is unnecessary as it was added in 5.2.0 (which
+            -- also adds support for :hovered and :pressed)
+            props = {bgimg = "", bgimg_pressed = ""},
+        }
+
+        -- Use the newer pressed selector as well in case the deprecated one is
+        -- removed
+        node[2] = {
+            type = "style",
+            selectors = {"\1:hovered", "\1:pressed"},
+            props = {bgimg = ""},
+        }
+
+        node[3] = {
             type = "image_button",
             texture_name = "blank.png",
             drawborder = false,
             x = 0, y = 0,
             w = node.w + extra_space, h = node.h,
-            label = node.label,
+            name = "\1", label = node.label,
         }
 
         -- Overlay button to prevent clicks from doing anything
-        node[2] = {
+        node[4] = {
             type = "image_button",
             texture_name = "blank.png",
             drawborder = false,
             x = 0, y = 0,
             w = node.w + extra_space, h = node.h,
-            label = "",
+            name = "\1", label = "",
         }
 
         node.y = node.y - LABEL_OFFSET
         node.label = nil
         node._label_hack = true
-        assert(#node == 2)
+        assert(#node == 4)
     end
 
     if node[w] then