use XMLGUI to add hamburger menu

works for KWrite, fails for Kate

apps/lib/data/kateui.rc

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE gui SYSTEM "kpartgui.dtd">
-<gui name="kate" version="98" translationDomain="kate">
+<gui name="kate" version="100" translationDomain="kate">
   <MenuBar>
     <Menu name="file" noMerge="1">
       <text>&amp;File</text>
@@ -151,6 +151,8 @@
     <DefineGroup name="find_operations"/>
     <Separator/>
     <DefineGroup name="zoom_operations"/>
+    <Spacer/>
+    <Action name="hamburger_menu" />
   </ToolBar>
   <Menu name="ktexteditor_popup" noMerge="1">
     <DefineGroup name="popup_operations"/>

apps/lib/katemainwindow.cpp

@@ -259,9 +259,7 @@ void KateMainWindow::setupImportantActions()
     a->setWhatsThis(i18n("Open a form to quick open documents."));
 
     // enable hamburger menu
-    auto hamburgerMenu = KStandardAction::hamburgerMenu(nullptr, nullptr, actionCollection());
-    QAction *const seperator = toolBar()->addSeparator();
-    toolBar()->insertAction(seperator, hamburgerMenu);
+    auto hamburgerMenu = static_cast<KHamburgerMenu *>(actionCollection()->addAction(KStandardAction::HamburgerMenu, QStringLiteral("hamburger_menu")));
     hamburgerMenu->setMenuBar(menuBar());
     hamburgerMenu->setShowMenuBarAction(m_paShowMenuBar);
 }