• Closing </th> tags are not written correctly when table row contains <td> </td> tags.
• Closing </th> is added after closing the row: </tr> </th>
• It would also be nice if a new line were stated after closing the table.

    || Heading1 || Heading2 | Heading3 |  Heading4 
    |  R1 C1    |  R1 C2    | R1 C3     |  R1 C4 
    |  R2 C1    |  R2 C2    | R2 C3     |  R2 C4 
    || R3 C1    |  R3 C2    | R3 C3     |  R3 C4 

<table class="wikitable" border="1">
<tr class="odd"> 
    <th> Heading1 </th> <th> Heading2 (!missing!)  <td> Heading3</td> <td>  Heading4 </td> </th> (placed here)
</tr>
<tr>
    <td>  R1 C1  </td> <td>  R1 C2  </td> <td> R1 C3  </td><td>  R1 C4 </td>
</tr>

<tr class="odd">
    <td>  R2 C1  </td> <td>  R2 C2    </td> <td> R2 C3 </td> <td>  R2 C4 </td>
</tr>
<tr>
   <th> R3 C1 (!missing!) <td>  R3 C2 </td><td> R3 C3 </td><td> R3 C4 </td> </th> (placed here)
</tr>

</table> 

Still fixed in 2.5.30...