Index: branches/5.1.x/core/admin_templates/js/uploader/uploader.js
===================================================================
diff -u -N -r12657 -r13086
--- branches/5.1.x/core/admin_templates/js/uploader/uploader.js	(.../uploader.js)	(revision 12657)
+++ branches/5.1.x/core/admin_templates/js/uploader/uploader.js	(.../uploader.js)	(revision 13086)
@@ -364,7 +364,7 @@
 	this._prepareFiles();
 
 	// sync position of all uploaders below current, because file queue height change will not affect their positions
-	UploadsManager.iterate('syncBrowseButton', 0);
+	UploadsManager.iterate('syncBrowseButton', 'timeout:0');
 }
 
 Uploader.prototype.removeFile = function (file) {
@@ -603,7 +603,7 @@
 }
 
 Uploader.prototype.disableBrowse = function($disabled) {
-	if (!isset($disabled)) {
+	if ($disabled === undefined) {
 		$disabled = true;
 	}