diff --git a/AppKit/CPWindow/CPWindow.j b/AppKit/CPWindow/CPWindow.j
index 933e03c90..c14103df9 100644
--- a/AppKit/CPWindow/CPWindow.j
+++ b/AppKit/CPWindow/CPWindow.j
@@ -791,6 +791,10 @@ CPTexturedBackgroundWindowMask
 - (void)setFrameOrigin:(CGPoint)anOrigin
 {
     [self _setClippedFrame:_CGRectMake(anOrigin.x, anOrigin.y, _CGRectGetWidth(_frame), _CGRectGetHeight(_frame)) display:YES animate:NO];
+
+    // reposition sheet       
+    if ([self attachedSheet])
+        [self _setAttachedSheetFrameOrigin];
 }
 
 /*!
@@ -1469,6 +1473,25 @@ CPTexturedBackgroundWindowMask
     var type = [anEvent type],
         point = [anEvent locationInWindow];
 
+    // If a sheet is attached events get filtered here.
+    // It is not clear what events should be passed to the view, perhaps all?
+    // CPLeftMouseDown is needed for window moving and resizing to work.
+    // CPMouseMoved is needed for rollover effects on title bar buttons.
+    if ([self attachedSheet])
+    {
+        switch (type)
+        {
+            case CPLeftMouseDown:
+                [_windowView mouseDown:anEvent];
+                break;
+            case CPMouseMoved:
+                [_windowView mouseMoved:anEvent];
+                break;
+        }
+        
+        return;
+    }
+
     switch (type)
     {
         case CPFlagsChanged:        return [[self firstResponder] flagsChanged:anEvent];
@@ -2245,7 +2268,9 @@ CPTexturedBackgroundWindowMask
         endFrame = CGRectMake(originx, originy, sheetFrame.size.width, sheetFrame.size.height);
 
     [[CPNotificationCenter defaultCenter] postNotificationName:CPWindowWillBeginSheetNotification object:self];
-    [CPApp runModalForWindow:aSheet];
+    
+    // old behavior; in Cocoa, sheets are not modal by default
+    //[CPApp runModalForWindow:aSheet];
 
     [aSheet orderFront:self];
     [aSheet setFrame:startFrame display:YES animate:NO];
diff --git a/AppKit/CPWindow/_CPWindowView.j b/AppKit/CPWindow/_CPWindowView.j
index 6a9f62894..e7936dd5a 100644
--- a/AppKit/CPWindow/_CPWindowView.j
+++ b/AppKit/CPWindow/_CPWindowView.j
@@ -140,7 +140,7 @@ var _CPWindowViewResizeIndicatorImage = nil;
         var newSize = CGSizeMake(CGRectGetWidth(_resizeFrame) + location.x - CGRectGetMinX(_resizeFrame), CGRectGetHeight(_resizeFrame) + location.y - CGRectGetMinY(_resizeFrame));
 
         if (theWindow._isSheet && theWindow._parentView && (theWindow._frame.size.width !== newSize.width))
-        [theWindow._parentView _setAttachedSheetFrameOrigin];
+            [theWindow._parentView _setAttachedSheetFrameOrigin];
 
         [theWindow setFrameSize:newSize];
     }
@@ -195,7 +195,6 @@ var _CPWindowViewResizeIndicatorImage = nil;
             location = [theWindow convertBaseToGlobal:[anEvent locationInWindow]],
             origin = [self _pointWithinScreenFrame:CGPointMake(_CGRectGetMinX(frame) + (location.x - _mouseDraggedPoint.x),
                                                                _CGRectGetMinY(frame) + (location.y - _mouseDraggedPoint.y))];
-
         [theWindow setFrameOrigin:origin];
 
         _mouseDraggedPoint = [self _pointWithinScreenFrame:location];
@@ -204,6 +203,17 @@ var _CPWindowViewResizeIndicatorImage = nil;
     [CPApp setTarget:self selector:@selector(trackMoveWithEvent:) forNextEventMatchingMask:CPLeftMouseDraggedMask | CPLeftMouseUpMask untilDate:nil inMode:nil dequeue:YES];
 }
 
+- (void)setFrameSize:(CGSize)newSize
+{
+    [super setFrameSize:newSize];
+ 
+    // reposition sheet if the parent window resizes or moves
+    var theWindow = [self window];
+       
+    if ([theWindow attachedSheet])
+        [theWindow _setAttachedSheetFrameOrigin];
+}	
+
 - (void)setShowsResizeIndicator:(BOOL)shouldShowResizeIndicator
 {
     if (shouldShowResizeIndicator)