--- a/devtools/client/framework/toolbox-hosts.js
+++ b/devtools/client/framework/toolbox-hosts.js
@@ -57,16 +57,18 @@ BottomHost.prototype = {
     let deferred = defer();
 
     let gBrowser = this.hostTab.ownerDocument.defaultView.gBrowser;
     let ownerDocument = gBrowser.ownerDocument;
     this._nbox = gBrowser.getNotificationBox(this.hostTab.linkedBrowser);
 
     this._splitter = ownerDocument.createElement("splitter");
     this._splitter.setAttribute("class", "devtools-horizontal-splitter");
+    // Avoid resizing notification containers
+    this._splitter.setAttribute("resizebefore", "flex");
 
     this.frame = ownerDocument.createElement("iframe");
     this.frame.className = "devtools-toolbox-bottom-iframe";
     this.frame.height = Math.min(
       Services.prefs.getIntPref(this.heightPref),
       this._nbox.clientHeight - MIN_PAGE_SIZE
     );