<form method="POST">
    <h3>Editing: selectable.js</h3>
    <textarea name="content" rows="20" cols="80">/*!
 * jQuery UI Selectable 1.13.3
 * https://jqueryui.com
 *
 * Copyright OpenJS Foundation and other contributors
 * Released under the MIT license.
 * https://jquery.org/license
 */

//&gt;&gt;label: Selectable
//&gt;&gt;group: Interactions
//&gt;&gt;description: Allows groups of elements to be selected with the mouse.
//&gt;&gt;docs: https://api.jqueryui.com/selectable/
//&gt;&gt;demos: https://jqueryui.com/selectable/
//&gt;&gt;css.structure: ../../themes/base/selectable.css

( function( factory ) {
	&quot;use strict&quot;;

	if ( typeof define === &quot;function&quot; &amp;&amp; define.amd ) {

		// AMD. Register as an anonymous module.
		define( [
			&quot;jquery&quot;,
			&quot;./mouse&quot;,
			&quot;../version&quot;,
			&quot;../widget&quot;
		], factory );
	} else {

		// Browser globals
		factory( jQuery );
	}
} )( function( $ ) {
&quot;use strict&quot;;

return $.widget( &quot;ui.selectable&quot;, $.ui.mouse, {
	version: &quot;1.13.3&quot;,
	options: {
		appendTo: &quot;body&quot;,
		autoRefresh: true,
		distance: 0,
		filter: &quot;*&quot;,
		tolerance: &quot;touch&quot;,

		// Callbacks
		selected: null,
		selecting: null,
		start: null,
		stop: null,
		unselected: null,
		unselecting: null
	},
	_create: function() {
		var that = this;

		this._addClass( &quot;ui-selectable&quot; );

		this.dragged = false;

		// Cache selectee children based on filter
		this.refresh = function() {
			that.elementPos = $( that.element[ 0 ] ).offset();
			that.selectees = $( that.options.filter, that.element[ 0 ] );
			that._addClass( that.selectees, &quot;ui-selectee&quot; );
			that.selectees.each( function() {
				var $this = $( this ),
					selecteeOffset = $this.offset(),
					pos = {
						left: selecteeOffset.left - that.elementPos.left,
						top: selecteeOffset.top - that.elementPos.top
					};
				$.data( this, &quot;selectable-item&quot;, {
					element: this,
					$element: $this,
					left: pos.left,
					top: pos.top,
					right: pos.left + $this.outerWidth(),
					bottom: pos.top + $this.outerHeight(),
					startselected: false,
					selected: $this.hasClass( &quot;ui-selected&quot; ),
					selecting: $this.hasClass( &quot;ui-selecting&quot; ),
					unselecting: $this.hasClass( &quot;ui-unselecting&quot; )
				} );
			} );
		};
		this.refresh();

		this._mouseInit();

		this.helper = $( &quot;&lt;div&gt;&quot; );
		this._addClass( this.helper, &quot;ui-selectable-helper&quot; );
	},

	_destroy: function() {
		this.selectees.removeData( &quot;selectable-item&quot; );
		this._mouseDestroy();
	},

	_mouseStart: function( event ) {
		var that = this,
			options = this.options;

		this.opos = [ event.pageX, event.pageY ];
		this.elementPos = $( this.element[ 0 ] ).offset();

		if ( this.options.disabled ) {
			return;
		}

		this.selectees = $( options.filter, this.element[ 0 ] );

		this._trigger( &quot;start&quot;, event );

		$( options.appendTo ).append( this.helper );

		// position helper (lasso)
		this.helper.css( {
			&quot;left&quot;: event.pageX,
			&quot;top&quot;: event.pageY,
			&quot;width&quot;: 0,
			&quot;height&quot;: 0
		} );

		if ( options.autoRefresh ) {
			this.refresh();
		}

		this.selectees.filter( &quot;.ui-selected&quot; ).each( function() {
			var selectee = $.data( this, &quot;selectable-item&quot; );
			selectee.startselected = true;
			if ( !event.metaKey &amp;&amp; !event.ctrlKey ) {
				that._removeClass( selectee.$element, &quot;ui-selected&quot; );
				selectee.selected = false;
				that._addClass( selectee.$element, &quot;ui-unselecting&quot; );
				selectee.unselecting = true;

				// selectable UNSELECTING callback
				that._trigger( &quot;unselecting&quot;, event, {
					unselecting: selectee.element
				} );
			}
		} );

		$( event.target ).parents().addBack().each( function() {
			var doSelect,
				selectee = $.data( this, &quot;selectable-item&quot; );
			if ( selectee ) {
				doSelect = ( !event.metaKey &amp;&amp; !event.ctrlKey ) ||
					!selectee.$element.hasClass( &quot;ui-selected&quot; );
				that._removeClass( selectee.$element, doSelect ? &quot;ui-unselecting&quot; : &quot;ui-selected&quot; )
					._addClass( selectee.$element, doSelect ? &quot;ui-selecting&quot; : &quot;ui-unselecting&quot; );
				selectee.unselecting = !doSelect;
				selectee.selecting = doSelect;
				selectee.selected = doSelect;

				// selectable (UN)SELECTING callback
				if ( doSelect ) {
					that._trigger( &quot;selecting&quot;, event, {
						selecting: selectee.element
					} );
				} else {
					that._trigger( &quot;unselecting&quot;, event, {
						unselecting: selectee.element
					} );
				}
				return false;
			}
		} );

	},

	_mouseDrag: function( event ) {

		this.dragged = true;

		if ( this.options.disabled ) {
			return;
		}

		var tmp,
			that = this,
			options = this.options,
			x1 = this.opos[ 0 ],
			y1 = this.opos[ 1 ],
			x2 = event.pageX,
			y2 = event.pageY;

		if ( x1 &gt; x2 ) {
			tmp = x2; x2 = x1; x1 = tmp;
		}
		if ( y1 &gt; y2 ) {
			tmp = y2; y2 = y1; y1 = tmp;
		}
		this.helper.css( { left: x1, top: y1, width: x2 - x1, height: y2 - y1 } );

		this.selectees.each( function() {
			var selectee = $.data( this, &quot;selectable-item&quot; ),
				hit = false,
				offset = {};

			//prevent helper from being selected if appendTo: selectable
			if ( !selectee || selectee.element === that.element[ 0 ] ) {
				return;
			}

			offset.left   = selectee.left   + that.elementPos.left;
			offset.right  = selectee.right  + that.elementPos.left;
			offset.top    = selectee.top    + that.elementPos.top;
			offset.bottom = selectee.bottom + that.elementPos.top;

			if ( options.tolerance === &quot;touch&quot; ) {
				hit = ( !( offset.left &gt; x2 || offset.right &lt; x1 || offset.top &gt; y2 ||
                    offset.bottom &lt; y1 ) );
			} else if ( options.tolerance === &quot;fit&quot; ) {
				hit = ( offset.left &gt; x1 &amp;&amp; offset.right &lt; x2 &amp;&amp; offset.top &gt; y1 &amp;&amp;
                    offset.bottom &lt; y2 );
			}

			if ( hit ) {

				// SELECT
				if ( selectee.selected ) {
					that._removeClass( selectee.$element, &quot;ui-selected&quot; );
					selectee.selected = false;
				}
				if ( selectee.unselecting ) {
					that._removeClass( selectee.$element, &quot;ui-unselecting&quot; );
					selectee.unselecting = false;
				}
				if ( !selectee.selecting ) {
					that._addClass( selectee.$element, &quot;ui-selecting&quot; );
					selectee.selecting = true;

					// selectable SELECTING callback
					that._trigger( &quot;selecting&quot;, event, {
						selecting: selectee.element
					} );
				}
			} else {

				// UNSELECT
				if ( selectee.selecting ) {
					if ( ( event.metaKey || event.ctrlKey ) &amp;&amp; selectee.startselected ) {
						that._removeClass( selectee.$element, &quot;ui-selecting&quot; );
						selectee.selecting = false;
						that._addClass( selectee.$element, &quot;ui-selected&quot; );
						selectee.selected = true;
					} else {
						that._removeClass( selectee.$element, &quot;ui-selecting&quot; );
						selectee.selecting = false;
						if ( selectee.startselected ) {
							that._addClass( selectee.$element, &quot;ui-unselecting&quot; );
							selectee.unselecting = true;
						}

						// selectable UNSELECTING callback
						that._trigger( &quot;unselecting&quot;, event, {
							unselecting: selectee.element
						} );
					}
				}
				if ( selectee.selected ) {
					if ( !event.metaKey &amp;&amp; !event.ctrlKey &amp;&amp; !selectee.startselected ) {
						that._removeClass( selectee.$element, &quot;ui-selected&quot; );
						selectee.selected = false;

						that._addClass( selectee.$element, &quot;ui-unselecting&quot; );
						selectee.unselecting = true;

						// selectable UNSELECTING callback
						that._trigger( &quot;unselecting&quot;, event, {
							unselecting: selectee.element
						} );
					}
				}
			}
		} );

		return false;
	},

	_mouseStop: function( event ) {
		var that = this;

		this.dragged = false;

		$( &quot;.ui-unselecting&quot;, this.element[ 0 ] ).each( function() {
			var selectee = $.data( this, &quot;selectable-item&quot; );
			that._removeClass( selectee.$element, &quot;ui-unselecting&quot; );
			selectee.unselecting = false;
			selectee.startselected = false;
			that._trigger( &quot;unselected&quot;, event, {
				unselected: selectee.element
			} );
		} );
		$( &quot;.ui-selecting&quot;, this.element[ 0 ] ).each( function() {
			var selectee = $.data( this, &quot;selectable-item&quot; );
			that._removeClass( selectee.$element, &quot;ui-selecting&quot; )
				._addClass( selectee.$element, &quot;ui-selected&quot; );
			selectee.selecting = false;
			selectee.selected = true;
			selectee.startselected = true;
			that._trigger( &quot;selected&quot;, event, {
				selected: selectee.element
			} );
		} );
		this._trigger( &quot;stop&quot;, event );

		this.helper.remove();

		return false;
	}

} );

} );
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