Correct controller size determination in wxToolbook.

The old code used the current toolbar size instead of determining its best
size for some strange reason and this resulted in toolbar remaining of tiny (1
pixel) height at least under wxGTK.

Fix this by simply using the best size of the toolbar.

Closes #11606.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63629 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/toolbkg.cpp

@@ -132,8 +132,7 @@ bool wxToolbook::Create(wxWindow *parent,
 wxSize wxToolbook::GetControllerSize() const
 {
     const wxSize sizeClient = GetClientSize(),
-                 sizeBorder = m_bookctrl->GetSize() - m_bookctrl->GetClientSize(),
-                 sizeToolBar = GetToolBar()->GetSize() + sizeBorder;
+                 sizeToolBar = GetToolBar()->GetBestSize();
 
     wxSize size;