cursor: always flush for immediate action

src/lib/render.c

@@ -1103,6 +1103,10 @@ int ncdirect_fg(ncdirect* nc, unsigned rgb){
 }
 
 int notcurses_cursor_enable(notcurses* nc, int y, int x){
+  if(nc->cursory >= 0 || nc->cursorx >= 0){
+    logerror(nc, "Cursor is already enabled\n");
+    return -1;
+  }
   if(y < 0 || x < 0){
     logerror(nc, "Illegal cursor placement: %d, %d\n", y, x);
     return -1;
@@ -1113,13 +1117,12 @@ int notcurses_cursor_enable(notcurses* nc, int y, int x){
   }
   if(nc->ttyfd >= 0){
     if(nc->tcache.cnorm){
-      if(stage_cursor(nc, nc->ttyfp, y, x) || fflush(nc->ttyfp)){
-        return -1;
-      }
-      nc->cursory = y;
-      nc->cursorx = x;
-      if(tty_emit("cnorm", nc->tcache.cnorm, nc->ttyfd) == 0){
-        return 0;
+      if(stage_cursor(nc, nc->ttyfp, y, x) == 0){
+        if(!tty_emit("cnorm", nc->tcache.cnorm, nc->ttyfd) && !fflush(nc->ttyfp)){
+          nc->cursory = y;
+          nc->cursorx = x;
+          return 0;
+        }
       }
     }
   }
@@ -1127,11 +1130,15 @@ int notcurses_cursor_enable(notcurses* nc, int y, int x){
 }
 
 int notcurses_cursor_disable(notcurses* nc){
-  nc->cursory = -1;
-  nc->cursorx = -1;
+  if(nc->cursorx < 0 || nc->cursory < 0){
+    logerror(nc, "Cursor is not enabled");
+    return -1;
+  }
   if(nc->ttyfd >= 0){
     if(nc->tcache.civis){
-      if(tty_emit("civis", nc->tcache.civis, nc->ttyfd) == 0){
+      if(!tty_emit("civis", nc->tcache.civis, nc->ttyfd) && !fflush(nc->ttyfp)){
+        nc->cursory = -1;
+        nc->cursorx = -1;
         return 0;
       }
     }
@@ -1140,7 +1147,12 @@ int notcurses_cursor_disable(notcurses* nc){
 }
 
 int notcurses_cursor_move_yx(notcurses* nc, int y, int x){
-  if(nc->cursory >= 0 && nc->cursorx >= 0){
+  if(nc->cursory < 0 || nc->cursorx < 0){
+    logerror(nc, "Cursor is not enabled");
+    return -1;
+  }
+  if(y < 0 || x < 0){
+    logerror(nc, "Illegal cursor placement: %d, %d\n", y, x);
     return -1;
   }
   if(stage_cursor(nc, nc->ttyfp, y, x) || fflush(nc->ttyfp)){