Bug 15886

Summary: LayoutTests/fast/events/mousedown_in_scrollbar.html crashes on WebKit/Qt
Product: WebKit Reporter: Holger Freyther <zecke>
Component: WebKit QtAssignee: George Staikos <staikos>
Severity: Normal    
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Other   
OS: OS X 10.4   
Description Flags
Do not crash on mousedown_in_scrollbar.html mjs: review+

Description Holger Freyther 2007-11-07 10:44:21 PST
The above test case crashes on WebKit/Qt and I would like to get some feedback:

PlatformScrollBarQt (created by the RenderLayer) can crash in two ways:
   1.) It was removed from the FrameView and it acceses parent()
   2.) m_client is a dangling pointer after RenderLayer was destroyed.

1.) is easy to fix
2.) Adding a ScrollBar::setClient and calling it from RenderLayer::destroyScrollBar to avoid the dangling pointer. I assume this approach will be declared too scientific so see the other alternative

EventHandler gives the PlatformScrollBar a 2nd live because m_lastScrollbarUnderMouse is a RefPtr and has the scrollbar stored. Rev 24942 introduced the test case and I extend the change to take m_lastScrollbarUnderMouse into consideration.
Comment 1 Holger Freyther 2007-11-07 10:46:02 PST
Created attachment 17112 [details]
Do not crash on mousedown_in_scrollbar.html

Change EventHandler to give up the reference to a Scrollbar created by the RenderLayer.
Comment 2 Holger Freyther 2007-11-29 21:52:53 PST
Finally landed in r28227.