Window decoration fixes for Wayland.

Allow setting no decorations, and an attempt to allow setting no title bar.
closes #15553


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74977 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/minifram.cpp

@@ -392,6 +392,7 @@ bool wxMiniFrame::Create( wxWindow *parent, wxWindowID id, const wxString &title
     gtk_container_add(GTK_CONTAINER(m_widget), eventbox);
 
     m_gdkDecor = 0;
+    gtk_window_set_decorated(GTK_WINDOW(m_widget), false);
     m_gdkFunc = 0;
     if (style & wxRESIZE_BORDER)
        m_gdkFunc = GDK_FUNC_RESIZE;