Implement setting bitmaps for the menu item for wxQt

Closes https://github.com/wxWidgets/wxWidgets/pull/975

docs/changes.txt

@@ -166,6 +166,7 @@ wxOSX:
 wxQt:
 
 - Fix menu bar background colour (Naser Buhamad).
+- Add support for bitmaps in menu items (Igor Korot).
 
 
 3.1.1: (released 2018-02-19)

include/wx/qt/menuitem.h

@@ -9,6 +9,8 @@
 #define _WX_QT_MENUITEM_H_
 
 #include "wx/menuitem.h"
+#include "wx/bitmap.h"
+
 class QAction;
 
 class WXDLLIMPEXP_FWD_CORE wxBitmap;
@@ -33,14 +35,15 @@ public:
     virtual void Check(bool check = true);
     virtual bool IsChecked() const;
 
-    void SetBitmap(const wxBitmap& bitmap);
-    const wxBitmap& GetBitmap() const;
+    virtual void SetBitmap(const wxBitmap& bitmap);
+    virtual const wxBitmap& GetBitmap() const { return m_bitmap; };
 
     virtual QAction *GetHandle() const;
 
 private:
     // Qt is using an action instead of a menu item.
     QAction *m_qtAction;
+    wxBitmap m_bitmap;
 
     wxDECLARE_DYNAMIC_CLASS( wxMenuItem );
 };

src/qt/menuitem.cpp

@@ -106,18 +106,17 @@ bool wxMenuItem::IsChecked() const
 }
 
 
-void wxMenuItem::SetBitmap(const wxBitmap& WXUNUSED(bitmap))
+void wxMenuItem::SetBitmap(const wxBitmap& bitmap)
 {
-    wxMISSING_FUNCTION();
-}
-
-const wxBitmap &wxMenuItem::GetBitmap() const
-{
-    wxMISSING_FUNCTION();
-
-    static wxBitmap s_bitmap;
-
-    return s_bitmap;
+    if ( m_kind == wxITEM_NORMAL )
+    {
+        m_bitmap = bitmap;
+        m_qtAction->setIcon( QIcon( *m_bitmap.GetHandle() ) );
+    }
+    else
+    {
+        wxFAIL_MSG("only normal menu items can have bitmaps");
+    }
 }
 
 QAction *wxMenuItem::GetHandle() const