Change background to rounded corners (#200)

This change is supposed to match the rounded inventory slot design.

init.lua

@@ -50,7 +50,7 @@ unified_inventory = {
 	trash_enabled = (minetest.settings:get_bool("unified_inventory_trash") ~= false),
 	imgscale = 1.25,
 	list_img_offset = 0.13,
-	standard_background = "background9[0,0;1,1;ui_formbg_9_sliced.png;true;16]",
+	standard_background = "bgcolor[#0000]background9[0,0;1,1;ui_formbg_9_sliced.png;true;16]",
 
 	version = 4
 }

internal.lua

@@ -115,9 +115,9 @@ local function formspec_add_categories(player, formspec, ui_peruser)
 		ui_peruser.form_header_y - (ui_peruser.is_lite_mode and 0 or 0.2)
 	}
 
-	formspec[n] = string.format("background9[%f,%f;%f,%f;%s;false;3]",
-		ui_peruser.page_x-0.1, categories_scroll_pos[2],
-		(ui_peruser.btn_spc * ui_peruser.pagecols) + 0.13, 1.4 + (ui_peruser.is_lite_mode and 0 or 0.2),
+	formspec[n] = string.format("background9[%f,%f;%f,%f;%s;false;16]",
+		ui_peruser.page_x-0.15, categories_scroll_pos[2],
+		(ui_peruser.btn_spc * ui_peruser.pagecols) + 0.2, 1.4 + (ui_peruser.is_lite_mode and 0 or 0.2),
 		"ui_smallbg_9_sliced.png")
 	n = n + 1