Keystroke popagation: properly manage key handler return codes

The following return codes can be get from key handlers:
 - KEY_HANDLED
 - KEY_PROPAGATED
 - key to be handled by default handler

Previous implementation invalidated the third one

src/curses/ui_call_flow.c

@@ -1282,7 +1282,7 @@ call_flow_handle_key(PANEL *panel, int key)
                 break;
             case ACTION_CLEAR_CALLS:
                 // Propagate the key to the previous panel
-                return -1;
+                return KEY_PROPAGATED;
 
             default:
                 // Parse next action

src/curses/ui_call_raw.c

@@ -269,7 +269,7 @@ call_raw_handle_key(PANEL *panel, int key)
                 break;
             case ACTION_CLEAR_CALLS:
                 // Propagate the key to the previous panel
-                return -1;
+                return KEY_PROPAGATED;
             default:
                 // Parse next action
                 continue;

src/curses/ui_manager.c

@@ -330,23 +330,24 @@ wait_for_input()
             continue;
 
         // Handle received key
-        int hdl = -1;
-        while (hdl != KEY_HANDLED) {
+        int key = c;
+        while (c != KEY_HANDLED) {
             // Check if current panel has custom bindings for that key
-            hdl = ui_handle_key(ui, c);
+            c = ui_handle_key(ui, c);
 
-            if (hdl == KEY_HANDLED) {
+            if (c == KEY_HANDLED) {
                 // Panel handled this key
                 continue;
-            } else if (hdl == KEY_PROPAGATED) {
+            } else if (c == KEY_PROPAGATED) {
+                // restore the key value
+                c = key;
                 // Destroy current panel
                 ui_destroy(ui);
                 // Try to handle this key with the previus panel
                 ui = ui_find_by_panel(panel_below(NULL));
             } else {
                 // Key not handled by UI nor propagated. Use default handler
-                default_handle_key(ui, c);
-                break;
+                c = default_handle_key(ui, c);
             }
         }
     }
@@ -402,8 +403,8 @@ default_handle_key(ui_t *ui, int key)
         break;
     }
 
-    // Return this is a valid handled key
-    return (action == ERR) ? key : 0;
+    // Consider the key handled at this point
+    return KEY_HANDLED;
 }
 
 void

src/curses/ui_manager.h

@@ -304,7 +304,7 @@ wait_for_input();
 /**
  * @brief Default handler for keys
  *
- * If ui doesn't handle the given key (ui_handle_key returns -1)
+ * If ui doesn't handle the given key (ui_handle_key returns the key value)
  * then the default handler will be invoked
  *
  * @param ui Current displayed UI structure