Background of DropDown menu

[Limbopo]

Hello.
For example we have this dropdown menu.

HWGA = {}
 
HWGA.Checkboxes = {
   title = "Select checkboxes",
   menu = {
      Key_1 = "Value 1",
      Key_2 = "Value 2",
      Key_3 = "Value 3",
      Key_4 = "Value 4",
      Key_5 = "Value 5",
   }
}
 
HWGA.ActiveCheckboxes = {}
 
 
function HWGADropDown_SetFlag(self, flag_name)
   if HWGA.ActiveCheckboxes[flag_name] then
      HWGA.ActiveCheckboxes[flag_name] = nil;
      self.checked = false;
   else
      HWGA.ActiveCheckboxes[flag_name] = true;
      self.checked = true;
   end
end
 
function HWGADropDown_Initialize(self)
   local info = UIDropDownMenu_CreateInfo();
   
   info.text = HWGA.Checkboxes .title;
   info.isTitle = true;
   info.notCheckable = true;
   UIDropDownMenu_AddButton(info);
   
   for flag_name, flag_value in pairs(HWGA.Checkboxes.menu) do
      info = UIDropDownMenu_CreateInfo();
      info.text = flag_name;
      info.value = flag_value;
      info.checked = HWGA.ActiveCheckboxes[flag_name];
      info.func = HWGADropDown_SetFlag;
      info.arg1 = flag_name;
      info.isNotRadio = true;
      info.keepShownOnClick = true;
      UIDropDownMenu_AddButton(info);
   end
end
 
local drp_dwn_button = CreateFrame("Button", "HereWeGoAgainDropDownButton", UIParent, "TooltipBackdropTemplate");
drp_dwn_button:SetSize(200, 40);
drp_dwn_button:SetPoint("CENTER", UIParent, "CENTER", 0, 0);
drp_dwn_button:SetScript("OnMouseDown", function(self) ToggleDropDownMenu(1, nil, HereWeGoAgainMenuDropDown, self, 0, 0) end);
 
local text = drp_dwn_button:CreateFontString(nil, "OVERLAY", "GameFontNormal");
text:SetPoint("CENTER", drp_dwn_button, "CENTER", 0, 0);
text:SetText(HWGA.Checkboxes.title);
 
local drp_dwn_frame = CreateFrame("Frame", "HereWeGoAgainMenuDropDown", nil, "UIDropDownMenuTemplate");
UIDropDownMenu_Initialize(drp_dwn_frame, HWGADropDown_Initialize, "MENU")

Is there is any simple way to change background color/opacity only for this dropdown?
In example, I want this:


I've found only one way to do it, but it changes every dropdown in a game, because it's in dependecies with DropDownList:

local BlackLayout = {
        ["TopRightCorner"] = {atlas = "Tooltip-NineSlice-CornerTopRight"},
        ["TopLeftCorner"] = {atlas = "Tooltip-NineSlice-CornerTopLeft"},
        ["BottomLeftCorner"] = {atlas = "Tooltip-NineSlice-CornerBottomLeft"},
        ["BottomRightCorner"] = {atlas = "Tooltip-NineSlice-CornerBottomRight"},
        ["TopEdge"] = {atlas = "_Tooltip-NineSlice-EdgeTop"},
        ["BottomEdge"] = {atlas = "_Tooltip-NineSlice-EdgeBottom"},
        ["LeftEdge"] = {atlas = "!Tooltip-NineSlice-EdgeLeft"},
        ["RightEdge"] = {atlas = "!Tooltip-NineSlice-EdgeRight"},
        ["Center"] = {layer = "BACKGROUND", atlas = "ui-frame-party-backgroundtile", x = -4, y = 4, x1 = 4, y1 = -4}
    }
 
    NineSliceUtil.ApplyLayout(DropDownList1MenuBackdrop, BlackLayout )

I didn't find any similar threads, but it seems to me that this question was of interest to many people.

I've tried SetBackdrop/different layouts, but it is not working. What I'm doing wrong?