Added a fix to taskbar; minor mods to help controllers; added justification

options to wxButton and wxBitmapButton


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_2_BRANCH@7235 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/helpchm.cpp

@@ -59,7 +59,8 @@ bool wxCHMHelpController::Initialize(const wxString& filename)
 
 bool wxCHMHelpController::LoadFile(const wxString& file)
 {
-    m_helpFile = file;
+    if (!file.IsEmpty())
+        m_helpFile = file;
     return TRUE;
 }