1 files changed, 39 insertions, 2 deletions
diff --git a/src/nvim/aucmd.c b/src/nvim/aucmd.c
index a9a7d834a4..32c77fa288 100644
--- a/src/nvim/aucmd.c
+++ b/src/nvim/aucmd.c
@@ -8,6 +8,8 @@
 #include "nvim/ui.h"
 #include "nvim/aucmd.h"
 #include "nvim/eval.h"
+#include "nvim/ex_getln.h"
+#include "nvim/buffer.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "aucmd.c.generated.h"
@@ -50,12 +52,47 @@ void aucmd_schedule_focusgained(bool gained)
 static void do_autocmd_focusgained(bool gained)
 {
   static bool recursive = false;
+  static Timestamp last_time = (time_t)0;
+  bool need_redraw = false;
 
   if (recursive) {
     return;  // disallow recursion
   }
   recursive = true;
-  apply_autocmds((gained ? EVENT_FOCUSGAINED : EVENT_FOCUSLOST),
-                 NULL, NULL, false, curbuf);
+  need_redraw |= apply_autocmds((gained ? EVENT_FOCUSGAINED : EVENT_FOCUSLOST),
+                                NULL, NULL, false, curbuf);
+
+  // When activated: Check if any file was modified outside of Vim.
+  // Only do this when not done within the last two seconds as:
+  // 1. Some filesystems have modification time granularity in seconds. Fat32
+  //    has a granularity of 2 seconds.
+  // 2. We could get multiple notifications in a row.
+  if (gained && last_time + (Timestamp)2000 < os_now()) {
+    need_redraw = check_timestamps(true);
+    last_time = os_now();
+  }
+
+  if (need_redraw) {
+    // Something was executed, make sure the cursor is put back where it
+    // belongs.
+    need_wait_return = false;
+
+    if (State & CMDLINE) {
+      redrawcmdline();
+    } else if ((State & NORMAL) || (State & INSERT)) {
+      if (must_redraw != 0) {
+        update_screen(0);
+      }
+
+      setcursor();
+    }
+
+    ui_flush();
+  }
+
+  if (need_maketitle) {
+    maketitle();
+  }
+
   recursive = false;
 }