Note: this list is generated by looking for the string for this theme hook, so it may include some references that are not actually using this theme hook.

ajax_pre_render_element in core/includes/ajax.inc
Adds Ajax information about an element to communicate with JavaScript.
BackdropWebTestCase::handleForm in core/modules/simpletest/backdrop_web_test_case.php
Handle form input related to backdropPost(). Ensure that the specified fields exist and attempt to create POST data in the correct manner for the particular field type.
backdrop_common_theme in core/includes/common.inc
Provides theme registration for themes across .inc files.
ckeditor_settings_form in core/modules/ckeditor/ckeditor.admin.inc
Editor settings callback; Provide options for CKEditor module.
CommonBackdropRenderTestCase::testBackdropRenderFormElements in core/modules/simpletest/tests/common.test
Test rendering form elements without passing through form_builder().
config_export_single_form in core/modules/config/config.admin.inc
Form callback; Builds the form for exporting a single configuration file.
config_import_single_form in core/modules/config/config.admin.inc
Form callback; Build the form to import a single configuration file.
contact_category_edit_form in core/modules/contact/contact.admin.inc
Form constructor for the category edit form.
contact_personal_form in core/modules/contact/contact.pages.inc
Form constructor for the personal contact form.
contact_site_form in core/modules/contact/contact.pages.inc
Form constructor for the site-wide contact form.
email_example_form in modules/examples/email_example/email_example.module
The contact form.
field_permission_example_field_widget_form in modules/examples/field_permission_example/field_permission_example.module
Implements hook_field_widget_form().
field_ui_field_edit_form in core/modules/field_ui/field_ui.admin.inc
Form constructor for the field instance settings form.
file_type_form in core/modules/file/file.admin.inc
Form constructor for the file type settings form.
filter_element_info in core/modules/filter/filter.module
Implements hook_element_info().
FormsTestCase::testDisabledMarkup in core/modules/simpletest/tests/form.test
Verify markup for disabled form elements.
FormsTestCase::testRequiredFields in core/modules/simpletest/tests/form.test
Check several empty values for required forms elements.
form_example_states_form in modules/examples/form_example/form_example_states.inc
States demo form.
form_test_placeholder_test in core/modules/simpletest/tests/form_test.module
Builds a form to test the placeholder attribute.
installer_manager_install_form in core/modules/installer/installer.manager.inc
Form constructor for the install form of the Installer module.
locale_translate_edit_form in core/modules/locale/locale.pages.inc
User interface for string editing.
menu_edit_item in core/modules/menu/menu.admin.inc
Menu callback; Build the menu link editing form.
menu_edit_menu in core/modules/menu/menu.admin.inc
Menu callback; Build the form that handles the adding/editing of a custom menu.
menu_form_node_form_alter in core/modules/menu/menu.module
Implements hook_form_BASE_FORM_ID_alter().
node_form in core/modules/node/node.pages.inc
Form constructor for the node add/edit form.
node_type_form in core/modules/node/node.types.inc
Form constructor for the node type editing form.
PathLayoutAccess::form in core/modules/layout/plugins/access/path_layout_access.inc
Settings form for configuring this access item.
path_patterns_settings_form in core/modules/path/path.admin.inc
Form builder; Configure the URL alias pattern settings.
syslog_form_system_logging_settings_alter in core/modules/syslog/syslog.module
Implements hook_form_FORM_ID_alter().
system_element_info in core/modules/system/system.module
Implements hook_element_info().
system_rss_feeds_settings in core/modules/system/system.admin.inc
Form builder; Configure how the site handles RSS feeds.
system_site_maintenance_mode in core/modules/system/system.admin.inc
Form builder; Configure the site's maintenance status.
text_field_widget_form in core/modules/field/modules/text/text.module
Implements hook_field_widget_form().
token_example_example_form in modules/examples/token_example/token_example.module
Form builder; display lists of supported token entities and text to tokenize.
update_settings in core/modules/update/update.admin.inc
Form constructor for the update settings form.
user_admin_settings in core/modules/user/user.admin.inc
Form builder; Configure user settings for this site.
user_settings_email in core/modules/user/user.admin.inc
Form builder; Configure user email settings for this site.
views_handler_area_result::options_form in core/modules/views/handlers/views_handler_area_result.inc
Default options form that provides the label widget that all fields should have.
views_handler_area_text_custom::options_form in core/modules/views/handlers/views_handler_area_text_custom.inc
Default options form that provides the label widget that all fields should have.
views_handler_field::options_form in core/modules/views/handlers/views_handler_field.inc
Default options form that provides the label widget that all fields should have.
views_handler_field_math::options_form in core/modules/views/handlers/views_handler_field_math.inc
Default options form that provides the label widget that all fields should have.
views_plugin_argument_default_php::options_form in core/modules/views/plugins/views_plugin_argument_default_php.inc
Provide the default form for setting options.
views_plugin_argument_validate_php::options_form in core/modules/views/plugins/views_plugin_argument_validate_php.inc
Provide the default form for setting options.
views_plugin_display::options_form in core/modules/views/plugins/views_plugin_display.inc
Provide the default form for setting options.
_form_options_expand in core/modules/field/modules/options/options.element.inc
Logic function for form_options_expand(). Do not call directly.
_form_test_disabled_elements in core/modules/simpletest/tests/form_test.module
Build a form to test disabled elements.