Fix unarchiving of BScrollView with layout

* We archive views using "managed" archives, and the children are not
attached in the BView(BMessage*) constructor, but later. So it's not
possible to find the target and scrollbars in the constructor of
BScrollView.
* Make BScrollView override AllUnarchived and find the target and
scrollbars again there. The code is slightly different as there is no
guarantee that the first child will be the target in that case. The
existing code in the constructor is preserved for non-managed archives.

headers/os/interface/ScrollView.h

@@ -34,6 +34,7 @@ public:
 
 	static	BArchivable*		Instantiate(BMessage* archive);
 	virtual	status_t			Archive(BMessage* archive, bool deep = true) const;
+	virtual status_t			AllUnarchived(const BMessage* archive);
 
 	// Hook methods
 	virtual	void				AllAttached();

src/kits/interface/ScrollView.cpp

@@ -70,6 +70,9 @@ BScrollView::BScrollView(BMessage* archive)
 		fTarget = NULL;
 
 	// search for our scroll bars
+	// This will not work for managed archives (when the layout kit is used).
+	// In that case the children are attached later, and we perform the search
+	// again in the AllUnarchived method.
 
 	fHorizontalScrollBar = NULL;
 	fVerticalScrollBar = NULL;
@@ -88,6 +91,7 @@ BScrollView::BScrollView(BMessage* archive)
 
 	fPreviousWidth = uint16(Bounds().Width());
 	fPreviousHeight = uint16(Bounds().Height());
+
 }
 
 
@@ -127,11 +131,58 @@ BScrollView::Archive(BMessage* archive, bool deep) const
 	// The highlighted state is not archived, but since it is
 	// usually (or should be) used to indicate focus, this
 	// is probably the right thing to do.
-
+	
 	return status;
 }
 
 
+status_t
+BScrollView::AllUnarchived(const BMessage* archive)
+{
+	status_t result = BView::AllUnarchived(archive);
+	if (result != B_OK)
+		return result;
+
+	// search for our scroll bars and target
+	int32 firstBar = 0;
+	BView* view;
+	while ((view = ChildAt(firstBar++)) != NULL) {
+		printf("scaning %s\n", view->Name());
+		BScrollBar *bar = dynamic_cast<BScrollBar *>(view);
+		// We assume that the first non-scrollbar child view is the target.
+		// So the target view can't be a BScrollBar, but who would do that?
+		if (bar == NULL) {
+			// in a shallow archive, we may not have a target anymore. We must
+			// be prepared for this case
+			if (fTarget == NULL && !archive->FindBool("_no_target_"))
+				fTarget = view;
+			continue;
+		}
+
+		if (bar->Orientation() == B_HORIZONTAL)
+			fHorizontalScrollBar = bar;
+		else if (bar->Orientation() == B_VERTICAL)
+			fVerticalScrollBar = bar;
+	}
+
+	printf("UA %p %p %p\n", fTarget, fHorizontalScrollBar, fVerticalScrollBar);
+
+	// Now connect the bars to the target, and make the target aware of them
+	if (fHorizontalScrollBar)
+		fHorizontalScrollBar->SetTarget(fTarget);
+	if (fVerticalScrollBar)
+		fVerticalScrollBar->SetTarget(fTarget);
+
+	if (fTarget)
+		fTarget->TargetedByScrollView(this);
+
+	fPreviousWidth = uint16(Bounds().Width());
+	fPreviousHeight = uint16(Bounds().Height());
+
+	return B_OK;
+}
+
+
 // #pragma mark - Hook methods
 
 
@@ -682,7 +733,7 @@ BScrollView::_Init(bool horizontal, bool vertical)
 			fTarget, 0, 1000, B_VERTICAL);
 		AddChild(fVerticalScrollBar);
 	}
-	
+
 	BRect targetFrame;
 	if (fTarget) {
 		// layout target and add it