patch 7.4.1895
Problem:    Cannot use a window ID where a window number is expected.
Solution:   Add LOWEST_WIN_ID, so that the window ID can be used where a
            number is expected.
diff --git a/src/window.c b/src/window.c
index 01da765..2dc2554 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4422,7 +4422,7 @@
 }
 #endif
 
-static int last_win_id = 0;
+static int last_win_id = LOWEST_WIN_ID - 1;
 
 /*
  * Allocate a window structure and link it in the window list when "hidden" is