ui: disable 'lazyredraw' during ui_refresh.

Could also try `do_redraw = true` instead of save/restore `p_lz`, but
the nice thing about save/restore of `p_lz` is that it is "atomic".
The semantics of `do_redraw` are not clear to me.

Closes #4884
References #6202
References https://github.com/neovim/neovim/pull/6202#issuecomment-284379503
References #3929 #5692 #6157
References #5866

2 files changed, 10 insertions, 7 deletions

diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index f8d519ab36..0c2c4a9bee 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -7440,13 +7440,11 @@ int number_width(win_T *wp)
   return n;
 }
 
-/*
- * Set size of the Vim shell.
- * If 'mustset' is TRUE, we must set Rows and Columns, do not get the real
- * window size (this is used for the :win command).
- * If 'mustset' is FALSE, we may try to get the real window size and if
- * it fails use 'width' and 'height'.
- */
+/// Set size of the Vim shell.
+/// If 'mustset' is TRUE, we must set Rows and Columns, do not get the real
+/// window size (this is used for the :win command).
+/// If 'mustset' is FALSE, we may try to get the real window size and if
+/// it fails use 'width' and 'height'.
 void screen_resize(int width, int height)
 {
   static int busy = FALSE;
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index a60c061949..b85a01814d 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -193,7 +193,12 @@ void ui_refresh(void)
   }
 
   row = col = 0;
+
+  int save_p_lz = p_lz;
+  p_lz = false;  // convince redrawing() to return true ...
   screen_resize(width, height);
+  p_lz = save_p_lz;
+
   for (UIWidget i = 0; (int)i < UI_WIDGETS; i++) {
     ui_set_external(i, ext_widgets[i]);
   }