demo: make debug plane 81 wide, with transparent last column

include/notcurses/notcurses.h

@@ -3675,7 +3675,7 @@ API void ncreader_destroy(struct ncreader* n, char** contents);
 
 // Dump selected Notcurses state to the supplied 'debugfp'. Output is freeform,
 // newline-delimited, and subject to change. It includes geometry of all
-// planes, from all piles. No line has more than 79 columns' worth of output.
+// planes, from all piles. No line has more than 80 columns' worth of output.
 API void notcurses_debug(const struct notcurses* nc, FILE* debugfp)
   __attribute__ ((nonnull (1, 2)));
 

src/demo/hud.c

@@ -101,8 +101,12 @@ debug_toggle(struct notcurses* nc){
     .y = 3,
     .x = NCALIGN_CENTER,
     .rows = count_debug_lines(output, outputlen) + 1,
-    .cols = 80,
+    // make it one column longer than the maximum debug output, so that a full
+    // line of output doesn't cause trigger a newline. we'll make the last
+    // column transparent.
+    .cols = 81,
     .flags = NCPLANE_OPTION_HORALIGNED,
+    .name = "dbg",
   };
   struct ncplane* n = ncplane_create(notcurses_stdplane(nc), &nopts);
   if(n == NULL){
@@ -121,6 +125,13 @@ debug_toggle(struct notcurses* nc){
     ncplane_destroy(n);
     return;
   }
+  for(int y = 0 ; y < ncplane_dim_y(n) ; ++y){
+    nccell c = CELL_TRIVIAL_INITIALIZER;
+    nccell_set_fg_alpha(&c, CELL_ALPHA_TRANSPARENT);
+    nccell_set_bg_alpha(&c, CELL_ALPHA_TRANSPARENT);
+    ncplane_putc_yx(n, y, ncplane_dim_x(n) - 1, &c);
+    nccell_release(n, &c);
+  }
   ncplane_putstr_aligned(n, ncplane_dim_y(n) - 1, NCALIGN_CENTER, "Press Alt+d to hide this window");
   free(output);
   debug = n;

src/lib/debug.c

@@ -63,7 +63,7 @@ ncpile_debug(const ncpile* p, FILE* debugfp){
   const ncplane* prev = NULL;
   int planeidx = 0;
   while(n){
-    fprintf(debugfp, "%04d off y: %3d x: %3d geom y: %3d x: %3d curs y: %3d x: %3d %p %.7s\n",
+    fprintf(debugfp, "%04d off y: %3d x: %3d geom y: %3d x: %3d curs y: %3d x: %3d %p %.4s\n",
             planeidx, n->absy, n->absx, n->leny, n->lenx, n->y, n->x, n, n->name);
     if(n->boundto || n->bnext || n->bprev || n->blist){
       fprintf(debugfp, " bound %p ← %p → %p binds %p\n",