Add minimal formspec prepend

mods/CORE/mcl_init/init.lua

@@ -1,12 +1,16 @@
 -- Some global variables (don't overwrite them!)
 mcl_vars = {}
 
---- GUI / inventory menu colors
+--- GUI / inventory menu settings
 mcl_vars.gui_slots = "listcolors[#9990;#FFF7;#FFF0;#000;#FFF]"
+-- nonbg is added as formspec prepend in mcl_formspec_prepend
+mcl_vars.gui_nonbg = mcl_vars.gui_slots
+
+-- Background stuff must be manually added by mods (no formspec prepend)
 mcl_vars.gui_bg = "bgcolor[#080808BB;true]"
 mcl_vars.gui_bg_img = ""
 
-mcl_vars.inventory_header = mcl_vars.gui_slots .. mcl_vars.gui_bg
+mcl_vars.inventory_header = mcl_vars.gui_bg
 
 -- Mapgen variables
 local mg_name = minetest.get_mapgen_setting("mg_name")

mods/HELP/mcl_craftguide/init.lua

@@ -315,8 +315,7 @@ function craftguide:get_formspec(player_name, is_fuel)
 	data.pagemax = max(1, ceil(#data.items / ipp))
 
 	local formspec = "size["..data.iX..","..(iY+3)..".6;]"..
-			mcl_vars.gui_slots ..
-			mcl_vars.gui_bg ..
+			mcl_vars.inventory_header..
 			[=[background[1,1;1,1;craftguide_bg.png;true]
 			button[2.4,0.21;0.8,0.5;search;?]
 			button[3.05,0.21;0.8,0.5;clear;X]

mods/HUD/mcl_formspec_prepend/depends.txt

@@ -0,0 +1 @@
+mcl_init

mods/HUD/mcl_formspec_prepend/init.lua

@@ -0,0 +1,3 @@
+minetest.register_on_joinplayer(function(player)
+	player:set_formspec_prepend(mcl_vars.gui_nonbg)
+end)

mods/HUD/mcl_formspec_prepend/mod.conf

@@ -0,0 +1 @@
+name = mcl_formspec_prepend