--- a/src/java.desktop/macosx/native/libawt_lwawt/awt/AWTWindow.m	Tue Oct 30 15:43:37 2018 +0530
+++ b/src/java.desktop/macosx/native/libawt_lwawt/awt/AWTWindow.m	Tue Oct 30 17:06:32 2018 +0530
@@ -214,7 +214,7 @@
     if (IS(styleBits, UNIFIED))       type |= NSUnifiedTitleAndToolbarWindowMask;
     if (IS(styleBits, UTILITY))       type |= NSUtilityWindowMask;
     if (IS(styleBits, HUD))           type |= NSHUDWindowMask;
-    if (IS(styleBits, SHEET))         type |= NSDocModalWindowMask;
+    if (IS(styleBits, SHEET))         type |= NSWindowStyleMaskDocModalWindow;
     if (IS(styleBits, NONACTIVATING)) type |= NSNonactivatingPanelMask;
 
     return type;
@@ -273,7 +273,12 @@
 {
 AWT_ASSERT_APPKIT_THREAD;
 
-    NSUInteger styleMask = [AWTWindow styleMaskForStyleBits:bits];
+    NSUInteger newBits = bits;
+    if (IS(bits, SHEET) && owner == nil) {
+        newBits = bits & ~NSWindowStyleMaskDocModalWindow;
+    }
+    NSUInteger styleMask = [AWTWindow styleMaskForStyleBits:newBits];
+
     NSRect contentRect = rect; //[NSWindow contentRectForFrameRect:rect styleMask:styleMask];
     if (contentRect.size.width <= 0.0) {
         contentRect.size.width = 1.0;
@@ -289,7 +294,8 @@
     if (IS(bits, UTILITY) ||
         IS(bits, NONACTIVATING) ||
         IS(bits, HUD) ||
-        IS(bits, HIDES_ON_DEACTIVATE))
+        IS(bits, HIDES_ON_DEACTIVATE) ||
+        IS(bits, SHEET))
     {
         self.nsWindow = [[AWTWindow_Panel alloc] initWithDelegate:self
                             frameRect:contentRect
@@ -319,6 +325,10 @@
         [self.nsWindow setCollectionBehavior:(1 << 8) /*NSWindowCollectionBehaviorFullScreenAuxiliary*/];
     }
 
+    if (IS(bits, SHEET) && owner != nil) {
+        [self.nsWindow setStyleMask: NSWindowStyleMaskDocModalWindow];
+    }
+
     return self;
 }