From 6825c60115df19208d1a094608c9b02707cc6af2 Mon Sep 17 00:00:00 2001
From: Esther Perelman <esther.perelman@sap.com>
Date: Wed, 29 Sep 2021 13:06:27 +0300
Subject: [PATCH] fix firefox strange behavior

---
 packages/core/src/browser/view-container.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/core/src/browser/view-container.ts b/packages/core/src/browser/view-container.ts
index 5fdcea9bb4011..9e77644502195 100644
--- a/packages/core/src/browser/view-container.ts
+++ b/packages/core/src/browser/view-container.ts
@@ -792,6 +792,7 @@ export class ViewContainer extends BaseWidget implements StatefulWidget, Applica
         return new DisposableCollection(
             addEventListener(part.headerElement, 'dragstart',
                 event => {
+                    event.preventDefault();
                     const mimeData = new MimeData();
                     mimeData.setData('application/vnd.phosphor.view-container-factory', () => part);
                     const clonedHeader = part.headerElement.cloneNode(true) as HTMLElement;