panelreel: add tablet curry accessors

include/notcurses.h

@@ -1430,6 +1430,9 @@ API struct tablet* panelreel_prev(struct panelreel* pr);
 // underlying WINDOW. Returns non-zero on failure.
 API int panelreel_destroy(struct panelreel* pr);
 
+API void* tablet_userptr(struct tablet* t);
+API const void* tablet_userptr_const(const struct tablet* t);
+
 #define PREFIXSTRLEN 7  // Does not include a '\0' (xxx.xxU)
 #define IPREFIXSTRLEN 8 //  Does not include a '\0' (xxxx.xxU)
 #define BPREFIXSTRLEN 9  // Does not include a '\0' (xxxx.xxUi), i == prefix

src/lib/panelreel.c

@@ -740,6 +740,14 @@ int panelreel_destroy(panelreel* preel){
   return ret;
 }
 
+void* tablet_userptr(tablet* t){
+  return t->curry;
+}
+
+const void* tablet_userptr_const(const tablet* t){
+  return t->curry;
+}
+
 int panelreel_tabletcount(const panelreel* preel){
   return preel->tabletcount;
 }