Merge pull request #2690 from zerline/focus-fix1

Fix focus() for Select.

Author: vidartf

packages/controls/src/widget_selection.ts

@@ -165,8 +165,6 @@ class DropdownView extends SelectionView {
             this.listbox.blur();
         }
     };
-
-    listbox: HTMLSelectElement;
 }
 
 
@@ -255,6 +253,17 @@ class SelectView extends SelectionView {
         this.model.set('index', this.listbox.selectedIndex, {updated_view: this});
         this.touch();
     }
+
+    /**
+     * Handle message sent to the front end.
+     */
+    handle_message(content: any) {
+        if (content.do == 'focus') {
+            this.listbox.focus();
+        } else if (content.do == 'blur') {
+            this.listbox.blur();
+        }
+    };
 }
 
 export