Turn off vsync throttling when macOS hardware sleeps (#927)

Speculative fix for [a freeze
issue](https://youtrack.jetbrains.com/issue/COMPOSE-1441/Desktop-skiko-freeze-after-sleep-on-Mac-with-multiple-external-monitors).

skiko/src/awtMain/objectiveC/macos/DisplayLinkThrottler.mm

@@ -24,6 +24,7 @@ static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
     NSScreen *_displayLinkScreen;
     CVDisplayLinkRef _displayLink;
     NSConditionLock *_vsyncConditionLock;
+    BOOL _isSleeping;
 }
 
 - (instancetype)init {
@@ -33,11 +34,34 @@ static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
         _displayLinkScreen = nil;
         _displayLink = nil;
         _vsyncConditionLock = [[NSConditionLock alloc] initWithCondition: 1];
+        _isSleeping = NO;
+
+        NSNotificationCenter *notificationCenter = [[NSWorkspace sharedWorkspace] notificationCenter];
+
+        [notificationCenter addObserver:self
+                            selector:@selector(systemWillSleep:)
+                            name:NSWorkspaceWillSleepNotification
+                            object:nil];
+
+        [notificationCenter addObserver:self
+                            selector:@selector(systemDidWake:)
+                            name:NSWorkspaceDidWakeNotification
+                            object:nil];
     }
 
     return self;
 }
 
+- (void)systemWillSleep:(NSNotification *)notification {
+    _isSleeping = YES;
+    [self invalidateDisplayLink];
+    [self onVSync];
+}
+
+- (void)systemDidWake:(NSNotification *)notification {
+    _isSleeping = NO;
+}
+
 - (void)onVSync {
     /// Lock condition lock and immediately unlock setting condition variable to 1 (can render now)
     [_vsyncConditionLock lock];
@@ -45,7 +69,7 @@ static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 }
 
 - (void)waitVSync {
-    /// If display link construction was corrupted, don't perform any waiting
+    /// If display link is not constructed (due to failure or explicit opt-out), don't perform any waiting
     if (!_displayLink) {
         return;
     }
@@ -65,6 +89,11 @@ static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 }
 
 - (void)setupDisplayLinkForWindow:(NSWindow *)window {
+    if (_isSleeping) {
+        /// System is sleeping, don't setup display link
+        return;
+    }
+
     NSScreen *screen = window.screen;
 
     if (!screen) {
@@ -136,6 +165,8 @@ JNIEXPORT void JNICALL Java_org_jetbrains_skiko_redrawer_DisplayLinkThrottler_wa
     DisplayLinkThrottler *throttler = (__bridge DisplayLinkThrottler *) (void *) throttlerPtr;
     NSWindow *window = (__bridge NSWindow *) (void *) windowPtr;
 
+    // CVDisplayLink is conditionally set up on each draw request to track window.screen change to match throttling
+    // with the refresh rate of the actual screen the window is shown on.
     [throttler setupDisplayLinkForWindow:window];
     [throttler waitVSync];
 }