При вводе в поисковике нашел вот что:
Very Small or Invisible Objects
Objects that are smaller than one or two pixels may not convert to 32-bit. To check if your application contains any of these tiny objects, select all of the objects in the application window and see if there are any selection handles around what appear to be empty areas. Delete any tiny objects before converting the application. (Sometimes the conversion will work if the tiny objects were grouped into a cell before the conversion, however it is better to delete these objects.)
Note Breaking up a wizard may result in tiny objects that have a dimension of zero pixels. When you first try to resize these objects, you will get the error
"WWHEAP /wwHeap_Free (address) Double-free detected. Continue?" Click Yes to continue (you may need to do this several times). Then delete the tiny objects. If you click No, WindowMaker will terminate.
Но как это связано с MBENETом