Disable CLIP_SIBLINGS style.

Fixes for getting best size.
Fixed some error in flag processing.    All according to patch #1523304.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40145 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/control.cpp

@@ -131,6 +131,9 @@ bool wxControl::OS2CreateControl( const wxChar*   zClassname,
     else
         label = m_label;
 
+    // clipping siblings does not yet work
+    dwStyle &= ~WS_CLIPSIBLINGS;
+
     m_hWnd = (WXHWND)::WinCreateWindow( (HWND)GetHwndOf(pParent) // Parent window handle
                                        ,(PSZ)zClass              // Window class
                                        ,(PSZ)label.c_str()       // Initial Text