Avoid gtk_widget_is_composited() with GTK+4

src/gtk/toplevel.cpp

@@ -1641,16 +1641,22 @@ bool wxTopLevelWindowGTK::CanSetTransparent()
         return wxSystemOptions::GetOptionInt(SYSOPT_TRANSPARENT) != 0;
     }
 
+#ifdef __WXGTK4__
+    return gdk_display_is_composited(gtk_widget_get_display(m_widget)) != 0;
+#else
 #if GTK_CHECK_VERSION(2,10,0)
     if (wx_is_at_least_gtk2(10))
     {
+        wxGCC_WARNING_SUPPRESS(deprecated-declarations)
         return gtk_widget_is_composited(m_widget) != 0;
+        wxGCC_WARNING_RESTORE()
     }
     else
 #endif // In case of lower versions than gtk+-2.10.0 we could look for _NET_WM_CM_Sn ourselves
     {
         return false;
     }
+#endif
 
 #if 0 // Don't be optimistic here for the sake of wxAUI
     int opcode, event, error;