macosx: added accessibility support to the main window (refs #495)

modules/gui/macosx/MainWindow.m

@@ -195,25 +195,45 @@ static VLCMainWindow *_o_sharedInstance = nil;
     [self useOptimizedDrawing: YES];
 
     [o_play_btn setToolTip: _NS("Play/Pause")];
+    [[o_play_btn cell] accessibilitySetOverrideValue:_NS("Click to play or pause the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_detached_play_btn setToolTip: [o_play_btn toolTip]];
+    [[o_detached_play_btn cell] accessibilitySetOverrideValue:_NS("Click to play or pause the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_bwd_btn setToolTip: _NS("Backward")];
+    [[o_bwd_btn cell] accessibilitySetOverrideValue:_NS("Click to go to the previous playlist item. Hold pressed to skip backwards through the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_detached_bwd_btn setToolTip: [o_bwd_btn toolTip]];
+    [[o_detached_bwd_btn cell] accessibilitySetOverrideValue:_NS("Click to go to the previous playlist item. Hold pressed to skip backwards through the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_fwd_btn setToolTip: _NS("Forward")];
+    [[o_fwd_btn cell] accessibilitySetOverrideValue:_NS("Click to go to the next playlist item. Hold pressed to skip forwards through the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_detached_fwd_btn setToolTip: [o_fwd_btn toolTip]];
+    [[o_detached_fwd_btn cell] accessibilitySetOverrideValue:_NS("Click to go to the next playlist item. Hold pressed to skip forwards through the current media.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_stop_btn setToolTip: _NS("Stop")];
+    [[o_stop_btn cell] accessibilitySetOverrideValue:_NS("Click to stop playback.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_playlist_btn setToolTip: _NS("Show/Hide Playlist")];
+    [[o_playlist_btn cell] accessibilitySetOverrideValue:_NS("Click to switch between video output and playlist. If no video is shown in the main window, this allows you to hide the playlist.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_repeat_btn setToolTip: _NS("Repeat")];
+    [[o_repeat_btn cell] accessibilitySetOverrideValue:_NS("Click to change repeat mode. There are 3 states: repeat one, repeat all and off.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_shuffle_btn setToolTip: _NS("Shuffle")];
+    [[o_shuffle_btn cell] accessibilitySetOverrideValue:_NS("Click to enable or disable random playback.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_effects_btn setToolTip: _NS("Effects")];
+    [[o_effects_btn cell] accessibilitySetOverrideValue:_NS("Click to show an Audio Effects panel featuring an equalizer and further filters.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_fullscreen_btn setToolTip: _NS("Toggle Fullscreen mode")];
+    [[o_fullscreen_btn cell] accessibilitySetOverrideValue:_NS("Click to enable fullscreen video playback.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_detached_fullscreen_btn setToolTip: [o_fullscreen_btn toolTip]];
+    [[o_detached_fullscreen_btn cell] accessibilitySetOverrideValue:_NS("Click to enable fullscreen video playback.") forAttribute:NSAccessibilityDescriptionAttribute];
     [[o_search_fld cell] setPlaceholderString: _NS("Search")];
+    [[o_search_fld cell] accessibilitySetOverrideValue:_NS("Enter a term to search the playlist. Results will be selected in the table.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_volume_sld setToolTip: _NS("Volume")];
+    [[o_volume_sld cell] accessibilitySetOverrideValue:_NS("Click and move the mouse while keeping the button pressed to use this slider to change the volume.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_volume_down_btn setToolTip: _NS("Mute")];
+    [[o_volume_down_btn cell] accessibilitySetOverrideValue:_NS("Click to mute or unmute the audio.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_volume_up_btn setToolTip: _NS("Full Volume")];
+    [[o_volume_up_btn cell] accessibilitySetOverrideValue:_NS("Click to play the audio at maximum volume.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_time_sld setToolTip: _NS("Position")];
+    [[o_time_sld cell] accessibilitySetOverrideValue:_NS("Click and move the mouse while keeping the button pressed to use this slider to change current playback position.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_detached_time_sld setToolTip: [o_time_sld toolTip]];
+    [[o_detached_time_sld cell] accessibilitySetOverrideValue:_NS("Click and move the mouse while keeping the button pressed to use this slider to change current playback position.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_dropzone_btn setTitle: _NS("Open media...")];
+    [[o_dropzone_btn cell] accessibilitySetOverrideValue:_NS("Click to open an advanced dialog to select the media to play. You can also drop files here to play.") forAttribute:NSAccessibilityDescriptionAttribute];
     [o_dropzone_lbl setStringValue: _NS("Drop media here")];
 
     if (!b_dark_interface) {