initialize m_labelWidget to 0 to fix crash when the label is empty (backport of part of r45312 changes from trunk)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@47628 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -115,6 +115,7 @@ wxMSW:
 - Added msw.font.no-proof-quality system option, see manual for description.
 - Fix appearance of notebook with non-top tabs under Windows Vista.
 - Fixed bug with symbol resolving in wxStackWalker (Axel Gembe).
+- Fixed showing busy cursor for disabled windows and during wxExecute()
 
 wxGTK:
 
@@ -139,6 +140,10 @@ wxMac:
 - Fixed ability of non-native/installed toolbars to have controls,
   in native toolbar compilation mode.
 
+wxMotif:
+
+- Fix crash when using wxStaticBox with empty label
+
 
 2.8.4
 -----

src/motif/statbox.cpp

@@ -94,6 +94,7 @@ bool wxStaticBox::Create(wxWindow *parent, wxWindowID id,
                         wxDefaultValidator, name ) )
         return false;
 
+    m_labelWidget = (WXWidget) 0;
     Widget parentWidget = (Widget) parent->GetClientWidget();
 
     m_mainWidget = XtVaCreateManagedWidget ("staticboxframe",