Streamline wxALWAYS_SHOW_SB handling in wxScrolled::Create()

[Mdx4]

If you use wxScrolledWindow with the wxALWAYS_SHOW_SB flag this leads to crash in initialization.

Probably could be related with "wxScrolled<> does not disable scrollbars when wxALWAYS_SHOW_SB is used" ?
http://trac.wxwidgets.org/changeset/72621
http://trac.wxwidgets.org/ticket/13616

GetClientSize is called too early and GetPeer() returns NULL.

How to reproduce it:

Index: samples/caret/caret.cpp
===================================================================
--- samples/caret/caret.cpp (revision 73027)
+++ samples/caret/caret.cpp (working copy)
@@ -306,7 +306,7 @@

MyCanvas::MyCanvas( wxWindow *parent )

: wxScrolledWindow( parent, wxID_ANY,

wxDefaultPosition, wxDefaultSize,

- wxSUNKEN_BORDER )
+ wxSUNKEN_BORDER | wxALWAYS_SHOW_SB )

{

m_text = (wxChar *)NULL;

[csomor]

Vadim: can we just invert the order of Create and SetScrollbar ? I'll commit a fix for OSX but if it can be done for all platforms without issues, I'd favor that, I don't understand why MSW does not trigger either

[SC]

(In [73041]) workaround, see #14856

[vadz]

Actually, is ShowScrollbars() call needed at all? In wxGTK and wxMSW it almost surely isn't because wxWindow already respects wxALWAYS_SHOW_SB.