Index: branches/5.2.x/core/admin_templates/incs/form_blocks.tpl
===================================================================
diff -u -N -r15804 -r15858
--- branches/5.2.x/core/admin_templates/incs/form_blocks.tpl	(.../form_blocks.tpl)	(revision 15804)
+++ branches/5.2.x/core/admin_templates/incs/form_blocks.tpl	(.../form_blocks.tpl)	(revision 15858)
@@ -721,12 +721,12 @@
 							function ($e) {
 								var $me = $(this);
 
-								if ($me.attr('disabled')) {
+								if ($me.prop('disabled')) {
 									return ;
 								}
 
 								var $type_selected = !isNaN( parseInt( $me.val() ) );
-								$( jq('#<inp2:$prefix_InputName name="$field"/>') ).attr('disabled', $type_selected ? '' : 'disabled');
+								$( jq('#<inp2:$prefix_InputName name="$field"/>') ).prop('disabled', !$type_selected);
 							}
 						)
 						.change();