Code:
     * The icon is optional, max length is 128 characters. When not using icons, just pass an empty string.
     * Icons are loaded from a subdirectory in the TeamSpeak client plugins folder. The subdirectory must be named like the
     * plugin filename, without dll/so/dylib suffix
     * e.g. for "test_plugin.dll", icon "1.png" is loaded from <TeamSpeak 3 Client install dir>\plugins\test_plugin\1.png

I remember it being something like
Code:
CREATE_MENU_ITEM(PLUGIN_MENU_TYPE_CLIENT,  MENU_ID_CLIENT_1,  "Test",  "style:ban.png");
is that right?