tetris: refresh on startup in place of erase()

src/tetris/background.h

@@ -8,7 +8,6 @@ void DrawBackground(const std::string& s) { // drawn to the standard plane
 }
 
 void DrawBoard() { // draw all fixed components of the game
-  stdplane_->erase();
   try{
     DrawBackground(BackgroundFile);
   }catch(...){

src/tetris/main.h

@@ -32,9 +32,10 @@ int main(void) {
   srand(time(nullptr));
   std::atomic_bool gameover = false;
   notcurses_options ncopts{};
-  ncopts.flags = NCOPTION_INHIBIT_SETLOCALE | NCOPTION_NO_ALTERNATE_SCREEN;
+  ncopts.flags = NCOPTION_INHIBIT_SETLOCALE;
   ncpp::NotCurses nc(ncopts);
   {
+    nc.refresh(nullptr, nullptr); // clear screen if smcup+background are unavailable
     Tetris t{nc, gameover};
     std::thread tid(&Tetris::Ticker, &t);
     if(IOLoop(nc, t, gameover)){