Hack wxMSW wxNotebook to show the text controls correctly initially.

Hack wxMSW wxNotebook to show the text controls correctly initially.

Add an Update() call to ensure that text controls in the initially selected
notebook page are shown correctly. It's almost certainly not the right fix for
the real bug that results in text controls not being shown when the notebook
comes up but it doesn't cost much and at least allows us to get correct
appearance for the themed notebooks.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69793 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775