Creating context popup menus

<element id="input-field">

  <input_field />
     <!-- ... -->

          <label type='theme_text'>Reset</label>

    <shortcut type='theme_text'>Alt-I</shortcut>

All supported theme widgets have an optional context element that uses create_popup_menu() to create a context popup menu. Its menu element generates the list layout manager for the context popup menu. An optional shortcut contains a keyboard x::w::shortcut value.

An append_copy_cut_paste in the popup menu adds standard Copy, Cut, and Paste menu items. Its parent should be its element's id. The context popup automatically takes care of update()ing these menu items before the popup gets shown. It is not necessary to add the code for that, like for Copy, Cut, and Paste in the main application menu.