Fix dialogs and menus when terminal is resized big->small->big

Used regular curses newwin WINDOWs before. Now uses newpad/subpad. The
buffers will be clipped correctly to the visible terminal area, and will
not be erased when the window is made too small and then resized to be
big again.

term_util.c

@@ -142,8 +142,13 @@ void qnav_stack_push(Qblock* qb, int height, int width) {
   }
   qnav_stack.blocks[qnav_stack.count] = qb;
   ++qnav_stack.count;
-  qb->outer_window = newwin(total_h, total_w, top, left);
-  qb->content_window = derwin(qb->outer_window, height, width, 1, 1);
+  qb->outer_window = newpad(total_h, total_w);
+  // This used to be derwin when when used newwin instead of newpad -- not sure
+  // if we should use derwin or subpad now. subpad is probably more compatible.
+  // ncurses docs state that it handles it correctly, unlike some others?
+  qb->content_window = subpad(qb->outer_window, height, width, 1, 1);
+  qb->y = top;
+  qb->x = left;
   qnav_stack.stack_changed = true;
 }
 

term_util.h

@@ -64,6 +64,7 @@ typedef struct {
   WINDOW* outer_window;
   WINDOW* content_window;
   char const* title;
+  int y, x;
 } Qblock;
 
 typedef struct {

tui_main.c

@@ -2668,6 +2668,9 @@ int main(int argc, char** argv) {
         wnoutrefresh(cont_window);
         drew_any = true;
       }
+      int term_h, term_w;
+      if (qnav_stack.count > 0) // todo lame, move this
+        getmaxyx(stdscr, term_h, term_w);
       for (Usz i = 0; i < qnav_stack.count; ++i) {
         Qblock* qb = qnav_stack.blocks[i];
         if (qnav_stack.stack_changed) {
@@ -2684,8 +2687,21 @@ int main(int argc, char** argv) {
             break;
           }
         }
-        touchwin(qb->outer_window);
-        wnoutrefresh(qb->outer_window);
+        touchwin(qb->outer_window); // here? or after continue?
+        if (term_h < 1 || term_w < 1)
+          continue;
+        int qbwin_h, qbwin_w;
+        getmaxyx(qb->outer_window, qbwin_h, qbwin_w);
+        int qbwin_endy = qb->y + qbwin_h;
+        int qbwin_endx = qb->x + qbwin_w;
+        if (qbwin_endy >= term_h)
+          qbwin_endy = term_h - 1;
+        if (qbwin_endx >= term_w)
+          qbwin_endx = term_w - 1;
+        if (qb->y >= qbwin_endy || qb->x >= qbwin_endx)
+          continue;
+        pnoutrefresh(qb->outer_window, 0, 0, qb->y, qb->x, qbwin_endy,
+                     qbwin_endx);
         drew_any = true;
       }
       qnav_stack.stack_changed = false;