If you try to add an activity in 2.0 that uses the $mform->addElement('modgrade'... function, a deprecated warning is generated.

For example, trying to add a forum:

link_to_popup_window() has been deprecated. Please change your code to use $OUTPUT->link().

• line 2474 of /lib/deprecatedlib.php: call to debugging()
• line ? of unknownfile: call to link_to_popup_window()
• line 71 of /lib/form/select.php: call to call_user_func_array()
• line 67 of /lib/form/modgrade.php: call to MoodleQuickForm_select->setHelpButton()
• line 366 of /lib/pear/HTML/QuickForm/element.php: call to MoodleQuickForm_modgrade->onQuickFormEvent()
• line 598 of /lib/pear/HTML/QuickForm/select.php: call to HTML_QuickForm_element->onQuickFormEvent()
• line 70 of /lib/form/modgrade.php: call to HTML_QuickForm_select->onQuickFormEvent()
• line 572 of /lib/pear/HTML/QuickForm.php: call to MoodleQuickForm_modgrade->onQuickFormEvent()
• line 602 of /lib/pear/HTML/QuickForm.php: call to HTML_QuickForm->_loadElement()
• line 94 of /mod/forum/mod_form.php: call to HTML_QuickForm->addElement() <=== Problem call
• line 149 of /lib/formslib.php: call to mod_forum_mod_form->definition()
• line 71 of /course/moodleform_mod.php: call to moodleform->moodleform()
• line 252 of /course/modedit.php: call to moodleform_mod->moodleform_mod()