3 files changed, 38 insertions, 1 deletions

diff --git a/music_sampler/app.py b/music_sampler/app.py
index 08a8891..ac1944a 100644
--- a/music_sampler/app.py
+++ b/music_sampler/app.py
@@ -7,6 +7,7 @@ kivy.require("1.9.1")
 from kivy.app import App
 from kivy.uix.floatlayout import FloatLayout
 from kivy.uix.relativelayout import RelativeLayout
+from kivy.uix.label import Label
 from kivy.properties import ListProperty, StringProperty
 from kivy.core.window import Window
 from kivy.lang import Builder
@@ -14,6 +15,7 @@ from kivy.lang import Builder
 register_fonts()
 
 
+from .helpers import Config
 from .key import Key
 from .mapping import Mapping
 
@@ -37,9 +39,23 @@ class KeyList(RelativeLayout):
         if len(self.keylist) > 2:
             self.third_key  = self.keylist[2]
 
-class Screen(FloatLayout):
+class UnfocusedOverlay(Label):
     pass
 
+class Screen(FloatLayout):
+    def __init__(self, **kwargs):
+        super(Screen, self).__init__(**kwargs)
+        self.unfocused_widget = UnfocusedOverlay()
+        Window.bind(focus=self.focus_changed)
+
+    def focus_changed(self, instance, focus):
+        if Config.no_focus_warning:
+            return
+        if not focus:
+            self.add_widget(self.unfocused_widget)
+        else:
+            self.remove_widget(self.unfocused_widget)
+
 class MusicSamplerApp(App):
     def build(self):
         Window.size = (913, 563)
diff --git a/music_sampler/helpers.py b/music_sampler/helpers.py
index 6acaba4..2249746 100644
--- a/music_sampler/helpers.py
+++ b/music_sampler/helpers.py
@@ -123,6 +123,10 @@ def parse_args():
             action=ListDevicesAction,
             help="List available sound devices"
             )
+    parser.add_argument("--no-focus-warning",
+            action='store_true',
+            help="Don't show warning when focus is lost"
+            )
     parser.add_argument('--',
             dest="args",
             help="Kivy arguments. All arguments after this are interpreted\
@@ -138,6 +142,7 @@ def parse_args():
     Config.channels = args.channels
     Config.sample_width = args.sample_width
     Config.builtin_mixing = args.builtin_mixing
+    Config.no_focus_warning = args.no_focus_warning
     if args.music_path.endswith("/"):
         Config.music_path = args.music_path
     else:
diff --git a/music_sampler/music_sampler.kv b/music_sampler/music_sampler.kv
index 7abab0d..ae5dbd7 100644
--- a/music_sampler/music_sampler.kv
+++ b/music_sampler/music_sampler.kv
@@ -76,6 +76,22 @@
     size_hint: None, None
     size: 2 * self.parent.width - 2 * self.parent.line_width, self.parent.height - key_label.font_size
 
+<UnfocusedOverlay>:
+  canvas.before:
+    Color:
+      rgba: 1, 0, 0, 0.9
+    Rectangle:
+      pos: 0, 0
+      size: self.width, self.height
+  size_hint: 1, 1
+  color: 1, 1, 1, 1
+  valign: "middle"
+  halign: "center"
+  font_name: "Ubuntu"
+  font_size: self.parent and 2 * self.parent.key_size or 42
+  text_size: self.size
+  text: "Focus lost!"
+
 <Screen>:
   canvas:
     Color: