patch 8.0.1123: cannot define a toolbar for a window

Problem:    Cannot define a toolbar for a window.
Solution:   Add a window-local toolbar.
diff --git a/src/window.c b/src/window.c
index 9b470f6..be8e20a 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4692,6 +4692,10 @@
     }
 #endif /* FEAT_GUI */
 
+#ifdef FEAT_MENU
+    remove_winbar(wp);
+#endif
+
 #ifdef FEAT_SYN_HL
     vim_free(wp->w_p_cc_cols);
 #endif
@@ -5667,6 +5671,7 @@
 
 /*
  * Set the height of a window.
+ * "height" excludes any window toolbar.
  * This takes care of the things inside the window, not what happens to the
  * window position, the frame or to other windows.
  */