Remove some unwanted items from the creative inventory

mods/default/init.lua

@@ -747,7 +747,7 @@ minetest.register_node("default:dirt_with_grass_footsteps", {
 	description = "Dirt with Grass and Footsteps",
 	tiles = {"default_grass_footsteps.png", "default_dirt.png", "default_dirt.png^default_grass_side.png"},
 	is_ground_content = true,
-	groups = {crumbly=3},
+	groups = {crumbly=3, not_in_creative_inventory=1},
 	drop = 'default:dirt',
 	sounds = default.node_sound_dirt_defaults({
 		footstep = {name="default_grass_footstep", gain=0.4},
@@ -1321,7 +1321,7 @@ minetest.register_node("default:furnace_active", {
 	paramtype2 = "facedir",
 	light_source = 8,
 	drop = "default:furnace",
-	groups = {cracky=2},
+	groups = {cracky=2, not_in_creative_inventory=1},
 	legacy_facedir_simple = true,
 	sounds = default.node_sound_stone_defaults(),
 	on_construct = function(pos)

mods/legacy/init.lua

@@ -102,6 +102,7 @@ minetest.register_craftitem(":cooked_rat", {
 minetest.register_craftitem(":firefly", {
 	description = "Firefly",
 	inventory_image = "firefly.png",
+	groups = {not_in_creative_inventory=1},
 	on_drop = function(item, dropper, pos)
 		minetest.env:add_firefly(pos)
 		item:take_item()