Qt without tiles again

"Qt without tiles" (commit ae4c180cf6)
two weeks ago accidentally took out a line that should have stayed.

win/Qt/qt_glyph.cpp

@@ -52,6 +52,7 @@ NetHackQtGlyphs::NetHackQtGlyphs()
 	if (!img.load(tile_file)) {
 	    QString msg;
             msg.sprintf("Cannot load 'nhtiles.bmp' or 'x11tiles'.");
+            QMessageBox::warning(0, "IO Error", msg);
             iflags.wc_ascii_map = 1;
             iflags.wc_tiled_map = 0;
 	} else {