patch 8.1.1391: no popup window support
Problem: No popup window support.
Solution: Add initial code for popup windows. Add the 'wincolor' option.
diff --git a/src/proto/buffer.pro b/src/proto/buffer.pro
index 5e1aa7a..1748fb5 100644
--- a/src/proto/buffer.pro
+++ b/src/proto/buffer.pro
@@ -61,6 +61,7 @@
int bt_terminal(buf_T *buf);
int bt_help(buf_T *buf);
int bt_prompt(buf_T *buf);
+int bt_popup(buf_T *buf);
int bt_nofile(buf_T *buf);
int bt_dontwrite(buf_T *buf);
int bt_dontwrite_msg(buf_T *buf);