patch 8.1.1548: popup_dialog() is not implemented
Problem: Popup_dialog() is not implemented.
Solution: Implement popup_dialog() and popup_filter_yesno().
diff --git a/src/globals.h b/src/globals.h
index 992ce2a..ec42984 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -599,7 +599,8 @@
EXTERN int aucmd_win_used INIT(= FALSE); /* aucmd_win is being used */
#ifdef FEAT_TEXT_PROP
-EXTERN win_T *first_popupwin; // first global popup window
+EXTERN win_T *first_popupwin; // first global popup window
+EXTERN win_T *popup_dragwin INIT(= NULL); // popup window being dragged
#endif
/*