+C<$content_string> is not HTML escaped.
+
+=back
+
+=head2 HIGH-LEVEL FUNCTIONS
+
+=over 4
+
+=item C<select_tag $name, $options_string, %attributes>
+
+Creates a HTML 'select' tag named C<$name> with the contents
+C<$options_string> and with arbitrary HTML attributes from
+C<%attributes>. The tag's C<id> defaults to C<name_to_id($name)>.
+
+The C<$options_string> is usually created by the
+L</options_for_select> function. If C<$options_string> is an array
+reference then it will be passed to L</options_for_select>
+automatically.
+
+=item C<input_tag $name, $value, %attributes>
+
+Creates a HTML 'input type=text' tag named C<$name> with the value
+C<$value> and with arbitrary HTML attributes from C<%attributes>. The
+tag's C<id> defaults to C<name_to_id($name)>.
+
+=item C<hidden_tag $name, $value, %attributes>
+
+Creates a HTML 'input type=hidden' tag named C<$name> with the value
+C<$value> and with arbitrary HTML attributes from C<%attributes>. The
+tag's C<id> defaults to C<name_to_id($name)>.
+
+=item C<submit_tag $name, $value, %attributes>
+
+Creates a HTML 'input type=submit class=submit' tag named C<$name> with the
+value C<$value> and with arbitrary HTML attributes from C<%attributes>. The
+tag's C<id> defaults to C<name_to_id($name)>.
+
+If C<$attributes{confirm}> is set then a JavaScript popup dialog will
+be added via the C<onclick> handler asking the question given with
+C<$attributes{confirm}>. If request is only submitted if the user
+clicks the dialog's ok/yes button.
+
+=item C<textarea_tag $name, $value, %attributes>
+
+Creates a HTML 'textarea' tag named C<$name> with the content
+C<$value> and with arbitrary HTML attributes from C<%attributes>. The
+tag's C<id> defaults to C<name_to_id($name)>.
+
+=item C<checkbox_tag $name, %attributes>
+
+Creates a HTML 'input type=checkbox' tag named C<$name> with arbitrary
+HTML attributes from C<%attributes>. The tag's C<id> defaults to
+C<name_to_id($name)>. The tag's C<value> defaults to C<1>.
+
+If C<%attributes> contains a key C<label> then a HTML 'label' tag is
+created with said C<label>. No attribute named C<label> is created in
+that case.
+
+If C<%attributes> contains a key C<checkall> then the value is taken as a
+JQuery selector and clicking this checkbox will also toggle all checkboxes
+matching the selector.
+
+=item C<date_tag $name, $value, cal_align =E<gt> $align_code, %attributes>
+
+Creates a date input field, with an attached javascript that will open a
+calendar on click. The javascript ist by default anchoered at the bottom right
+sight. This can be overridden with C<cal_align>, see Calendar documentation for
+the details, usually you'll want a two letter abbreviation of the alignment.
+Right + Bottom becomes C<BL>.
+
+=item C<radio_button_tag $name, %attributes>
+
+Creates a HTML 'input type=radio' tag named C<$name> with arbitrary
+HTML attributes from C<%attributes>. The tag's C<value> defaults to
+C<1>. The tag's C<id> defaults to C<name_to_id($name . "_" . $value)>.
+
+If C<%attributes> contains a key C<label> then a HTML 'label' tag is
+created with said C<label>. No attribute named C<label> is created in
+that case.
+
+=item C<javascript_tag $file1, $file2, $file3...>
+
+Creates a HTML 'E<lt>script type="text/javascript" src="..."E<gt>'
+tag for each file name parameter passed. Each file name will be
+postfixed with '.js' if it isn't already and prefixed with 'js/' if it
+doesn't contain a slash.
+
+=item C<stylesheet_tag $file1, $file2, $file3...>
+
+Creates a HTML 'E<lt>link rel="text/stylesheet" href="..."E<gt>' tag
+for each file name parameter passed. Each file name will be postfixed
+with '.css' if it isn't already and prefixed with 'css/' if it doesn't
+contain a slash.
+
+=item C<date_tag $name, $value, cal_align =E<gt> $align_code, %attributes>
+
+Creates a date input field, with an attached javascript that will open a
+calendar on click. The javascript ist by default anchoered at the bottom right
+sight. This can be overridden with C<cal_align>, see Calendar documentation for
+the details, usually you'll want a two letter abbreviation of the alignment.
+Right + Bottom becomes C<BL>.
+
+=item C<tabbed \@tab, %attributes>
+
+Will create a tabbed area. The tabs should be created with the helper function
+C<tab>. Example:
+
+ [% L.tabbed([
+ L.tab(LxERP.t8('Basic Data'), 'part/_main_tab.html'),
+ L.tab(LxERP.t8('Custom Variables'), 'part/_cvar_tab.html', if => SELF.display_cvar_tab),
+ ]) %]
+
+An optional attribute is C<selected>, which accepts the ordinal of a tab which
+should be selected by default.
+
+=item C<areainput_tag $name, $content, %PARAMS>
+
+Creates a generic input tag or textarea tag, depending on content size. The
+mount of desired rows must be given with C<rows> parameter, Accpeted parameters
+include C<min_rows> for rendering a minimum of rows if a textarea is displayed.
+
+You can force input by setting rows to 1, and you can force textarea by setting
+rows to anything >1.
+
+=item C<multiselect2side $id, %params>
+
+Creates a JavaScript snippet calling the jQuery function
+C<multiselect2side> on the select control with the ID C<$id>. The
+select itself is not created. C<%params> can contain the following
+entries:
+
+=over 2
+
+=item C<labelsx>
+
+The label of the list of available options. Defaults to the
+translation of 'Available'.
+
+=item C<labeldx>
+
+The label of the list of selected options. Defaults to the
+translation of 'Selected'.
+
+=back
+
+=item C<sortable_element $selector, %params>
+
+Makes the children of the DOM element C<$selector> (a jQuery selector)
+sortable with the I<jQuery UI Selectable> library. The children can be
+dragged & dropped around. After dropping an element an URL can be
+postet to with the element IDs of the sorted children.
+
+If this is used then the JavaScript file C<js/jquery-ui.js> must be
+included manually as well as it isn't loaded via C<$::form-gt;header>.
+
+C<%params> can contain the following entries:
+
+=over 2
+
+=item C<url>
+
+The URL to POST an AJAX request to after a dragged element has been
+dropped. The AJAX request's return value is ignored. If given then
+C<$params{with}> must be given as well.
+
+=item C<with>
+
+A string that is interpreted as the prefix of the children's ID. Upon
+POSTing the result each child whose ID starts with C<$params{with}> is
+considered. The prefix and the following "_" is removed from the
+ID. The remaining parts of the IDs of those children are posted as a
+single array parameter. The array parameter's name is either
+C<$params{as}> or, missing that, C<$params{with}>.
+
+=item C<as>
+
+Sets the POST parameter name for AJAX request after dropping an
+element (see C<$params{with}>).
+
+=item C<handle>
+
+An optional jQuery selector specifying which part of the child element
+is dragable. If the parameter is not given then it defaults to
+C<.dragdrop> matching DOM elements with the class C<dragdrop>. If the
+parameter is set and empty then the whole child element is dragable,
+and clicks through to underlying elements like inputs or links might
+not work.
+
+=item C<dont_recolor>
+
+If trueish then the children will not be recolored. The default is to
+recolor the children by setting the class C<listrow0> on odd and
+C<listrow1> on even entries.
+
+=back
+
+Example:
+
+ <script type="text/javascript" src="js/jquery-ui.js"></script>
+
+ <table id="thing_list">
+ <thead>
+ <tr><td>This</td><td>That</td></tr>
+ </thead>
+ <tbody>
+ <tr id="thingy_2"><td>stuff</td><td>more stuff</td></tr>
+ <tr id="thingy_15"><td>stuff</td><td>more stuff</td></tr>
+ <tr id="thingy_6"><td>stuff</td><td>more stuff</td></tr>
+ </tbody>
+ <table>
+
+ [% L.sortable_element('#thing_list tbody',
+ url => 'controller.pl?action=SystemThings/reorder',
+ with => 'thingy',
+ as => 'thing_ids',
+ recolor_rows => 1) %]
+
+After dropping e.g. the third element at the top of the list a POST
+request would be made to the C<reorder> action of the C<SystemThings>
+controller with a single parameter called C<thing_ids> -- an array
+containing the values C<[ 6, 2, 15 ]>.
+
+=item C<dump REF>
+
+Dumps the Argument using L<Data::Dumper> into a E<lt>preE<gt> block.
+
+=back
+
+=head2 CONVERSION FUNCTIONS
+
+=over 4
+
+=item C<options_for_select \@collection, %options>