Phoenix docs: rename the `richtextctrl_overview.rst` with the underscore and add the snipped for `dataview.TreeListCtrl.GetNextItem.1.py`

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@75889 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
`ThumbnailCtrl` on Phoenix: fix a ZeroDivisionError when the ThumbnailCtrl is minimized inside a AUI pane.

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@75890 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
AGW on Classic: Do not tile the `FlatNotebook` pages unless it is needed (seems like a bug in wx.SplitterWindow to me). Closes #15992.

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@75891 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775