Make dw_notebook_page_destroy() on OS/2 and Windows destroy the contents of the page. I found that on GTK the contents will have the reference count lowered when the page is removed. Causing the contents to be destroyed... however this does not happen on OS/2 or Windows. The option was to either reference the contents before destroying the page on GTK or have OS/2 and Windows destroy the contents. Because of the name I decided to destroy the contents. It isn't clear to me what the behavior of removeTabViewItem is on the Mac so no changes there.