UI: Update Levels Nodes

- Instead of making the enum expanded leave it in menu form.
- Use full words instead of letters.

Differential Revision: https://developer.blender.org/D12686

source/blender/editors/space_node/drawnode.cc

@@ -2079,7 +2079,7 @@ static void node_composit_buts_premulkey(uiLayout *layout, bContext *UNUSED(C),
 
 static void node_composit_buts_view_levels(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
-  uiItemR(layout, ptr, "channel", DEFAULT_FLAGS | UI_ITEM_R_EXPAND, nullptr, ICON_NONE);
+  uiItemR(layout, ptr, "channel", DEFAULT_FLAGS, "", ICON_NONE);
 }
 
 static void node_composit_buts_colorbalance(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)

source/blender/makesrna/intern/rna_nodetree.c

@@ -6545,11 +6545,11 @@ static void def_cmp_levels(StructRNA *srna)
   PropertyRNA *prop;
 
   static const EnumPropertyItem channel_items[] = {
-      {1, "COMBINED_RGB", 0, "C", "Combined RGB"},
-      {2, "RED", 0, "R", "Red Channel"},
-      {3, "GREEN", 0, "G", "Green Channel"},
-      {4, "BLUE", 0, "B", "Blue Channel"},
-      {5, "LUMINANCE", 0, "L", "Luminance Channel"},
+      {1, "COMBINED_RGB", 0, "Combined", "Combined RGB"},
+      {2, "RED", 0, "Red", "Red Channel"},
+      {3, "GREEN", 0, "Green", "Green Channel"},
+      {4, "BLUE", 0, "Blue", "Blue Channel"},
+      {5, "LUMINANCE", 0, "Luminance", "Luminance Channel"},
       {0, NULL, 0, NULL, NULL},
   };