[gnome-clocks/bilelmoussaoui/redesign-timer] Timer: don't allow setting an empty timer

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit 6a746bc59802f8ca4faf956d5cc7d8004126523d
Author: Bilal Elmoussaoui <bil elmoussaoui gmail com>
Date:   Tue Jan 28 06:23:52 2020 +0100

    Timer: don't allow setting an empty timer

 src/timer.vala | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/timer.vala b/src/timer.vala
index c3667b7..813fd2f 100644
--- a/src/timer.vala
+++ b/src/timer.vala
@@ -463,7 +463,10 @@ public class Face : Gtk.Stack, Clocks.Clock {
         no_timer_container.reorder_child(timer_setup, 0);
         set_visible_child_name ("empty");
 
-        // start_button.set_sensitive(false);
+        start_button.set_sensitive(false);
+        timer_setup.duration_changed.connect ((duration) => {
+            start_button.set_sensitive (duration.get_total_seconds () != 0);
+        });
         start_button.clicked.connect(() => {
             var timer = this.timer_setup.get_timer();
             this.add_timer(timer);