Correctly render containers when a split container is focused

include/con.h

@@ -68,6 +68,12 @@ bool con_is_floating(Con *con);
  */
 Con *con_inside_floating(Con *con);
 
+/**
+ * Checks if the given container is inside a focused container.
+ *
+ */
+Con *con_inside_focused(Con *con);
+
 /**
  * Returns the container with the given client window ID or NULL if no such
  * container exists.

src/con.c

@@ -358,6 +358,18 @@ Con *con_inside_floating(Con *con) {
     return con_inside_floating(con->parent);
 }
 
+/*
+ * Checks if the given container is inside a focused container.
+ *
+ */
+Con *con_inside_focused(Con *con) {
+    if (con == focused)
+        return true;
+    if (!con->parent)
+        return false;
+    return con_inside_focused(con->parent);
+}
+
 /*
  * Returns the container with the given client window ID or NULL if no such
  * container exists.

src/x.c

@@ -290,7 +290,7 @@ void x_draw_decoration(Con *con) {
     /* find out which colors to use */
     if (con->urgent)
         p->color = &config.client.urgent;
-    else if (con == focused)
+    else if (con == focused || con_inside_focused(con))
         p->color = &config.client.focused;
     else if (con == TAILQ_FIRST(&(parent->focus_head)))
         p->color = &config.client.focused_inactive;