diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/js/thickbox/thickbox.js
--- a/wp/wp-includes/js/thickbox/thickbox.js	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/js/thickbox/thickbox.js	Mon Oct 14 17:39:30 2019 +0200
@@ -18,9 +18,16 @@
 	imgLoader.src = tb_pathToImage;
 });
 
-//add thickbox to href & area elements that have a class of .thickbox
+/*
+ * Add thickbox to href & area elements that have a class of .thickbox.
+ * Remove the loading indicator when content in an iframe has loaded.
+ */
 function tb_init(domChunk){
-	jQuery('body').on('click', domChunk, tb_click);
+	jQuery( 'body' )
+		.on( 'click', domChunk, tb_click )
+		.on( 'thickbox:iframe:loaded', function() {
+			jQuery( '#TB_window' ).removeClass( 'thickbox-loading' );
+		});
 }
 
 function tb_click(){
@@ -34,17 +41,19 @@
 
 function tb_show(caption, url, imageGroup) {//function called when the user clicks on a thickbox link
 
+	var $closeBtn;
+
 	try {
 		if (typeof document.body.style.maxHeight === "undefined") {//if IE 6
 			jQuery("body","html").css({height: "100%", width: "100%"});
 			jQuery("html").css("overflow","hidden");
 			if (document.getElementById("TB_HideSelect") === null) {//iframe to hide select elements in ie6
-				jQuery("body").append("<iframe id='TB_HideSelect'>"+thickboxL10n.noiframes+"</iframe><div id='TB_overlay'></div><div id='TB_window'></div>");
+				jQuery("body").append("<iframe id='TB_HideSelect'>"+thickboxL10n.noiframes+"</iframe><div id='TB_overlay'></div><div id='TB_window' class='thickbox-loading'></div>");
 				jQuery("#TB_overlay").click(tb_remove);
 			}
 		}else{//all others
 			if(document.getElementById("TB_overlay") === null){
-				jQuery("body").append("<div id='TB_overlay'></div><div id='TB_window'></div>");
+				jQuery("body").append("<div id='TB_overlay'></div><div id='TB_window' class='thickbox-loading'></div>");
 				jQuery("#TB_overlay").click(tb_remove);
 				jQuery( 'body' ).addClass( 'modal-open' );
 			}
@@ -130,7 +139,7 @@
 
 			TB_WIDTH = imageWidth + 30;
 			TB_HEIGHT = imageHeight + 60;
-			jQuery("#TB_window").append("<a href='' id='TB_ImageOff'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><img id='TB_Image' src='"+url+"' width='"+imageWidth+"' height='"+imageHeight+"' alt='"+caption+"'/></a>" + "<div id='TB_caption'>"+caption+"<div id='TB_secondLine'>" + TB_imageCount + TB_PrevHTML + TB_NextHTML + "</div></div><div id='TB_closeWindow'><a href='#' id='TB_closeWindowButton'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><div class='tb-close-icon'></div></a></div>");
+			jQuery("#TB_window").append("<a href='' id='TB_ImageOff'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><img id='TB_Image' src='"+url+"' width='"+imageWidth+"' height='"+imageHeight+"' alt='"+caption+"'/></a>" + "<div id='TB_caption'>"+caption+"<div id='TB_secondLine'>" + TB_imageCount + TB_PrevHTML + TB_NextHTML + "</div></div><div id='TB_closeWindow'><button type='button' id='TB_closeWindowButton'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><span class='tb-close-icon'></span></button></div>");
 
 			jQuery("#TB_closeWindowButton").click(tb_remove);
 
@@ -195,15 +204,15 @@
 					urlNoQuery = url.split('TB_');
 					jQuery("#TB_iframeContent").remove();
 					if(params['modal'] != "true"){//iframe no modal
-						jQuery("#TB_window").append("<div id='TB_title'><div id='TB_ajaxWindowTitle'>"+caption+"</div><div id='TB_closeAjaxWindow'><a href='#' id='TB_closeWindowButton'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><div class='tb-close-icon'></div></a></div></div><iframe frameborder='0' hspace='0' src='"+urlNoQuery[0]+"' id='TB_iframeContent' name='TB_iframeContent"+Math.round(Math.random()*1000)+"' onload='tb_showIframe()' style='width:"+(ajaxContentW + 29)+"px;height:"+(ajaxContentH + 17)+"px;' >"+thickboxL10n.noiframes+"</iframe>");
+						jQuery("#TB_window").append("<div id='TB_title'><div id='TB_ajaxWindowTitle'>"+caption+"</div><div id='TB_closeAjaxWindow'><button type='button' id='TB_closeWindowButton'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><span class='tb-close-icon'></span></button></div></div><iframe frameborder='0' hspace='0' allowtransparency='true' src='"+urlNoQuery[0]+"' id='TB_iframeContent' name='TB_iframeContent"+Math.round(Math.random()*1000)+"' onload='tb_showIframe()' style='width:"+(ajaxContentW + 29)+"px;height:"+(ajaxContentH + 17)+"px;' >"+thickboxL10n.noiframes+"</iframe>");
 					}else{//iframe modal
 					jQuery("#TB_overlay").unbind();
-						jQuery("#TB_window").append("<iframe frameborder='0' hspace='0' src='"+urlNoQuery[0]+"' id='TB_iframeContent' name='TB_iframeContent"+Math.round(Math.random()*1000)+"' onload='tb_showIframe()' style='width:"+(ajaxContentW + 29)+"px;height:"+(ajaxContentH + 17)+"px;'>"+thickboxL10n.noiframes+"</iframe>");
+						jQuery("#TB_window").append("<iframe frameborder='0' hspace='0' allowtransparency='true' src='"+urlNoQuery[0]+"' id='TB_iframeContent' name='TB_iframeContent"+Math.round(Math.random()*1000)+"' onload='tb_showIframe()' style='width:"+(ajaxContentW + 29)+"px;height:"+(ajaxContentH + 17)+"px;'>"+thickboxL10n.noiframes+"</iframe>");
 					}
 			}else{// not an iframe, ajax
 					if(jQuery("#TB_window").css("visibility") != "visible"){
 						if(params['modal'] != "true"){//ajax no modal
-						jQuery("#TB_window").append("<div id='TB_title'><div id='TB_ajaxWindowTitle'>"+caption+"</div><div id='TB_closeAjaxWindow'><a href='#' id='TB_closeWindowButton'><div class='tb-close-icon'></div></a></div></div><div id='TB_ajaxContent' style='width:"+ajaxContentW+"px;height:"+ajaxContentH+"px'></div>");
+						jQuery("#TB_window").append("<div id='TB_title'><div id='TB_ajaxWindowTitle'>"+caption+"</div><div id='TB_closeAjaxWindow'><button type='button' id='TB_closeWindowButton'><span class='screen-reader-text'>"+thickboxL10n.close+"</span><span class='tb-close-icon'></span></button></div></div><div id='TB_ajaxContent' style='width:"+ajaxContentW+"px;height:"+ajaxContentH+"px'></div>");
 						}else{//ajax modal
 						jQuery("#TB_overlay").unbind();
 						jQuery("#TB_window").append("<div id='TB_ajaxContent' class='TB_modal' style='width:"+ajaxContentW+"px;height:"+ajaxContentH+"px;'></div>");
@@ -231,7 +240,9 @@
 					jQuery("#TB_load").remove();
 					jQuery("#TB_window").css({'visibility':'visible'});
 				}else{
-					jQuery("#TB_ajaxContent").load(url += "&random=" + (new Date().getTime()),function(){//to do a post change this load method
+					var load_url = url;
+					load_url += -1 === url.indexOf('?') ? '?' : '&';
+					jQuery("#TB_ajaxContent").load(load_url += "random=" + (new Date().getTime()),function(){//to do a post change this load method
 						tb_position();
 						jQuery("#TB_load").remove();
 						tb_init("#TB_ajaxContent a.thickbox");
@@ -250,6 +261,16 @@
 			});
 		}
 
+		$closeBtn = jQuery( '#TB_closeWindowButton' );
+		/*
+		 * If the native Close button icon is visible, move focus on the button
+		 * (e.g. in the Network Admin Themes screen).
+		 * In other admin screens is hidden and replaced by a different icon.
+		 */
+		if ( $closeBtn.find( '.tb-close-icon' ).is( ':visible' ) ) {
+			$closeBtn.focus();
+		}
+
 	} catch(e) {
 		//nothing here
 	}
@@ -258,13 +279,16 @@
 //helper functions below
 function tb_showIframe(){
 	jQuery("#TB_load").remove();
-	jQuery("#TB_window").css({'visibility':'visible'});
+	jQuery("#TB_window").css({'visibility':'visible'}).trigger( 'thickbox:iframe:loaded' );
 }
 
 function tb_remove() {
  	jQuery("#TB_imageOff").unbind("click");
 	jQuery("#TB_closeWindowButton").unbind("click");
-	jQuery("#TB_window").fadeOut("fast",function(){jQuery('#TB_window,#TB_overlay,#TB_HideSelect').trigger("tb_unload").unbind().remove();});
+	jQuery( '#TB_window' ).fadeOut( 'fast', function() {
+		jQuery( '#TB_window, #TB_overlay, #TB_HideSelect' ).trigger( 'tb_unload' ).unbind().remove();
+		jQuery( 'body' ).trigger( 'thickbox:removed' );
+	});
 	jQuery( 'body' ).removeClass( 'modal-open' );
 	jQuery("#TB_load").remove();
 	if (typeof document.body.style.maxHeight == "undefined") {//if IE 6