Editing WoW:Using UIDropDownMenu (section)

== Step 3 : Initialization ==
If you skipped [[#Step 2 : The Menu]], you must add an ''OnLoad'' function to your button in the following fashion. This will display the menu in the first style specified in [[#Step 1 : The Button]].

   <Frame parent="UIParent">
        <Frames>
            <Button name="MyDropDownMenuButton">
                <Scripts>
                    <OnLoad>
                        UIDropDownMenu_Initialize(self, MyDropDownMenu_OnLoad);
                    </OnLoad>
                
                    <OnClick>
                        MyDropDownMenuButton_OnClick();
                    </OnClick>
                </Scripts>
            </Button>
        </Frames>
    </Frame>

As you have seen from the example, the third variable in ''UIDropDownMenu_Initialize'' changes the appearance of the menu. If the third variable is nil, the menu will be displayed in the fashion of the first example shown in [[#Step 1 : The Button]]. If the third variable is "MENU", which requires the initialization to occur in a separate frame outside of the button as shown in [[#Step 2 : The Menu]], the menu will be displayed in the fashion of the second example shown in [[#Step 1 : The Button]].

The ''OnLoad'' function itself should be as follows. This example adds one option to the menu.

    function MyDropDownMenu_OnLoad()
        info            = {};
        info.text       = "This is an option in the menu.";
        info.value      = "OptionVariable";
        info.func       = FunctionCalledWhenOptionIsClicked 
                  -- can also be done as function() FunctionCalledWhenOptionIsClicked() end;
        
        -- Add the above information to the options menu as a button.
        UIDropDownMenu_AddButton(info);
    end

Note that careless use of throw-away tables can make your addon generate a lot of unnecessary memory garbage. This is especially true I you don't create menu only once, but recreate it dynamically every time it is displayed to place check marks or any other dynamic content where it needed. See [[HOWTO: Use Tables Without Generating Extra Garbage]] for some advices on how to minimize or eliminate completely garbage generation in such cases.