Create a small helper class for Unity global menu bug workaround.

Encapsulate the code temporarily incrementing wxOpenModalDialogsCount in a
small helper class to make it easier to reuse it elsewhere.

See #14823.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73689 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dialog.cpp

@@ -23,9 +23,7 @@
 
 #include <gtk/gtk.h>
 #include "wx/gtk/private/gtk2-compat.h"
-
-// this is defined in src/gtk/toplevel.cpp
-extern int wxOpenModalDialogsCount;
+#include "wx/gtk/private/dialogcount.h"
 
 wxDEFINE_TIED_SCOPED_PTR_TYPE(wxGUIEventLoop)
 
@@ -172,7 +170,7 @@ int wxDialog::ShowModal()
 
     m_modalShowing = true;
 
-    wxOpenModalDialogsCount++;
+    wxOpenModalDialogLocker modalLock;
 
     // NOTE: gtk_window_set_modal internally calls gtk_grab_add() !
     gtk_window_set_modal(GTK_WINDOW(m_widget), TRUE);
@@ -190,8 +188,6 @@ int wxDialog::ShowModal()
 
     gtk_window_set_modal(GTK_WINDOW(m_widget), FALSE);
 
-    wxOpenModalDialogsCount--;
-
     return GetReturnCode();
 }