Handle wxALWAYS_SHOW_SB in wxOSX.

Initialize m_[hv]ScrollBarAlwaysShown to true if this flag is given when
creating the window.

Closes #15344.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74567 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/window_osx.cpp

@@ -416,6 +416,9 @@ bool wxWindowMac::Create(wxWindowMac *parent,
 
     m_windowVariant = parent->GetWindowVariant() ;
 
+    m_hScrollBarAlwaysShown =
+    m_vScrollBarAlwaysShown = HasFlag(wxALWAYS_SHOW_SB);
+
     if ( m_peer != kOSXNoWidgetImpl )
     {
         SetPeer(wxWidgetImpl::CreateUserPane( this, parent, id, pos, size , style, GetExtraStyle() ));