Tracker: Fix #8388.

BNavigator shouldn't update its location until AllAttached(). Otherwise,
it might immediately trigger a redraw, and in such a case, the
navigation buttons wouldn't yet have had a chance to load their icon
resources, leading to a debug assert in BPictureButton due to said
images not being present, but required.

src/kits/tracker/Navigator.cpp

@@ -179,9 +179,6 @@ BNavigator::~BNavigator()
 void
 BNavigator::AttachedToWindow()
 {
-	// Inital setup of widget states
-	UpdateLocation(0, kActionSet);
-
 	// All messages should arrive here
 	fBack->SetTarget(this);
 	fForw->SetTarget(this);
@@ -190,6 +187,14 @@ BNavigator::AttachedToWindow()
 }
 
 
+void
+BNavigator::AllAttached()
+{
+	// Inital setup of widget states
+	UpdateLocation(0, kActionSet);
+}
+
+
 void
 BNavigator::Draw(BRect)
 {

src/kits/tracker/Navigator.h

@@ -98,6 +98,7 @@ protected:
 	virtual void Draw(BRect rect);
 	virtual void MessageReceived(BMessage* msg);
 	virtual void AttachedToWindow();
+	virtual	void AllAttached();
 
 	void GoForward(bool option); // is option key held down?
 	void GoBackward(bool option);