Cell: non-OPAQUE always sets non-default bit

include/notcurses/notcurses.h

@@ -1035,7 +1035,7 @@ channel_set_alpha(unsigned* channel, int alpha){
     return -1;
   }
   *channel = (alpha << CELL_ALPHA_SHIFT) | (*channel & ~CELL_ALPHA_MASK);
-  if(alpha != CELL_ALPHA_HIGHCONTRAST){
+  if(alpha != CELL_ALPHA_OPAQUE){
     *channel |= CELL_BGDEFAULT_MASK;
   }
   return 0;

tests/cell.cpp

@@ -120,7 +120,7 @@ SUBCASE("SetItalic") {
     CHECK(0 == cell_set_bg_alpha(&c, CELL_ALPHA_TRANSPARENT));
     CHECK(CELL_ALPHA_TRANSPARENT == cell_bg_alpha(&c));
     CHECK(cell_fg_default_p(&c));
-    CHECK(cell_bg_default_p(&c));
+    CHECK(!cell_bg_default_p(&c));
   }
 
   // common teardown

tests/notcurses.cpp

@@ -124,7 +124,7 @@ TEST_CASE("NotcursesBase") {
     CHECK(0 > channels_set_bg_alpha(&channel, CELL_ALPHA_HIGHCONTRAST));
     CHECK(CELL_ALPHA_TRANSPARENT == channels_bg_alpha(channel));
     CHECK(channels_fg_default_p(channel));
-    CHECK(channels_bg_default_p(channel));
+    CHECK(!channels_bg_default_p(channel));
   }
 
   SUBCASE("Stats"){