Merge branch 'fixbug-1549' of https://github.com/alexgleason/wagtail into alexgleason-fixbug-1549

wagtail/wagtailadmin/static_src/wagtailadmin/js/blocks/stream.js

@@ -30,9 +30,18 @@
             self.container.addClass('stream-menu-closed');
         };
 
+        self.addFirstBlock = function() {
+            if (opts.onChooseBlock) opts.onChooseBlock(opts.childBlocks[0]);
+        };
+
         self.toggle = function() {
             if (self.container.hasClass('stream-menu-closed')) {
-                self.show();
+                if (opts.childBlocks.length == 1) {
+                    /* If there's only one block type, add it automatically */
+                    self.addFirstBlock();
+                } else {
+                    self.show();
+                }
             } else {
                 self.hide();
             }