Dark Mode doesn't work on OS X 10.10

Received the following crash report:


Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib          0x00007fff98545286 __pthread_kill + 10
1   libsystem_c.dylib               0x00007fff8cd1bb53 abort + 129
2   libc++abi.dylib                 0x00007fff8b62ca21 abort_message + 257
3   libc++abi.dylib                 0x00007fff8b6549d1 default_terminate_handler() + 267
4   libobjc.A.dylib                 0x00007fff8cabd7d6 _objc_terminate() + 103
5   libc++abi.dylib                 0x00007fff8b6520a1 std::__terminate(void (*)()) + 8
6   libc++abi.dylib                 0x00007fff8b651b30 __cxa_throw + 121
7   libobjc.A.dylib                 0x00007fff8cab9898 objc_exception_throw + 341
8   com.apple.CoreFoundation        0x00007fff92a53e1a +[NSException raise:format:arguments:] + 106
9   com.apple.Foundation            0x00007fff910608cb -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 195
10  com.apple.AppKit                0x00007fff935f142a -[NSVisualEffectView _setInternalMaterialType:] + 129
11  com.sappharad.MP3Gain-Express   0x000000010eeb3eb5 -[M3GWindow awakeFromNib] + 462
12  com.apple.CoreFoundation        0x00007fff92960bdf -[NSSet makeObjectsPerformSelector:] + 223
13  com.apple.AppKit                0x00007fff935e014d -[NSIBObjectData nibInstantiateWithOwner:options:topLevelObjects:] + 1216
14  com.apple.AppKit                0x00007fff935bf205 loadNib + 384
15  com.apple.AppKit                0x00007fff935be72b +[NSBundle(NSNibLoading) _loadNibFile:nameTable:options:withZone:ownerBundle:] + 313
16  com.apple.AppKit                0x00007fff935be4e7 -[NSBundle(NSNibLoading) loadNibNamed:owner:topLevelObjects:] + 201
17  com.apple.AppKit                0x00007fff935be2b3 +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 344
18  com.apple.AppKit                0x00007fff935b6e89 NSApplicationMain + 605
19  com.sappharad.MP3Gain-Express   0x000000010eeb1370 start + 52

The crash occurs when setting the Window vibrancy layer to Ultra Dark. As it turns out, Ultra Dark was not added until OS X 10.11, and the standard dark layer style isn't dark enough in my opinion to look good in this situation.

So to fix this, I'm increasing the minimum requirement for dark mode to OS X 10.11 or later.

Sappharad / mp3gainOSX

Dark Mode doesn't work on OS X 10.10 #19