TextPopup is an internal function. It contains right-click popup menu options for editing text. If you right-click in a text area box you will see the TextPopup menu.

To add items to this menu from the menus.cfg you can:

1. Go to Configuration > Menus to open the config in a text editor.
2. Add a line beginning with TextPopup like the example below.
3. Create your item using the syntax described in the default config file.
4. Save menus.cfg and re-start K-Meleon.

This example would add a duplicate SpellChecker item to K-Meleon's menu:

!TextPopup {
  Spellcheck=spellcheck(here)
}

You can find more information about custom configurations on the ConfigFiles page.

You can also add items to this menu with macros. An example of the syntax would be:

setmenu("TextPopup",macro,_("Item text"),"item_Macro");