tdf#121267 Handle missing diagonal borders

Regression of 9125a4f3
("Use FeatureStateEvent directly for status updates").

Change-Id: I57856c5707fffcf84f95afa9ef80a394b550c56f
Reviewed-on: https://gerrit.libreoffice.org/63497
Tested-by: Jenkins
Reviewed-by: Maxim Monastirsky <momonasmon@gmail.com>

svx/source/tbxctrls/tbcontrl.cxx

@@ -1952,8 +1952,13 @@ bool BorderColorStatus::statusChanged( const css::frame::FeatureStateEvent& rEve
     else
     {
         css::table::BorderLine2 aTable;
-        if ( rEvent.IsEnabled && ( rEvent.State >>= aTable ) )
-            aColor = Color(aTable.Color);
+        if ( rEvent.IsEnabled )
+            rEvent.State >>= aTable;
+
+        SvxBorderLine aLine;
+        SvxBoxItem::LineToSvxLine( aTable, aLine, false );
+        if ( !aLine.isEmpty() )
+            aColor = aLine.GetColor();
 
         if ( rEvent.FeatureURL.Complete == ".uno:BorderTLBR" )
         {