fix initial display of default image

direct/src/plugin/p3dInstance.cxx

@@ -2211,6 +2211,7 @@ make_splash_window() {
       // download it directly.  This one won't be cached locally
       // (though the browser might be free to cache it).
       _image_files[i]._use_standard_image = false;
+      _image_files[i]._filename.clear();
       string image_url = _fparams.lookup_token(token_keyword);
       if (image_url.empty()) {
         // No splash image.  Never mind.

direct/src/plugin/p3dX11SplashWindow.cxx

@@ -108,6 +108,7 @@ set_visible(bool visible) {
 ////////////////////////////////////////////////////////////////////
 void P3DX11SplashWindow::
 set_image_filename(const string &image_filename, ImagePlacement image_placement) {
+  nout << "image_filename = " << image_filename << "\n";
   if (_subprocess_pid == -1) {
     return;
   }