From bab61a93d6167a552a76e538ec2929bf3eb3bb36 Mon Sep 17 00:00:00 2001
From: Albrecht Schlosser <albrechts.fltk@online.de>
Date: Tue, 12 Mar 2019 17:21:53 +0100
Subject: Prevent unnecessary Fl_Clock timer events (STR 3516)

See documentation @ STR 3516
---
 src/Fl_Clock.cxx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Fl_Clock.cxx b/src/Fl_Clock.cxx
index a9271452b..ca7237212 100644
--- a/src/Fl_Clock.cxx
+++ b/src/Fl_Clock.cxx
@@ -213,7 +213,10 @@ static void tick(void *v) {
   int usec;
   Fl::system_driver()->gettime(&sec, &usec);
   ((Fl_Clock*)v)->value((ulong)sec);
-  Fl::add_timeout((1000000 - usec)/1000000., tick, v); // time till next second
+
+  // schedule timer event slightly later than the next second (+25 ms)
+  // to prevent multiple timer events if triggered too early (STR 3516)
+  Fl::add_timeout((1025000 - usec)/1000000., tick, v);
 }
 
 int Fl_Clock::handle(int event) {
-- 
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