If you select the whole table along with some content and click BOLD, all table related tags will get wrapped by a <strong> tag. For instance tfoot, thead and so on will be wrapped with <strong>.

Initial content:

<table style="width: 0px;">
    <colgroup><col /><col /><col /></colgroup>
    <thead>
        <tr>
            <th>test</th>
            <th>test</th>
            <th>test</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <th>test</th>
            <th>test</th>
            <td>test</td>
        </tr>
        <tr>
            <th>test</th>
            <th>test</th>
            <td>test</td>
        </tr>
    </tbody>
</table>
<br />
test line beneath the table



Modified content:

   
<table style="width: 0px;">
<strong><colgroup><col /><col /><col /></colgroup></strong>
    <thead>
        <tr>
            <th><strong>test</strong></th>
            <th><strong>test</strong></th>
            <th><strong>test</strong></th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <th><strong>test</strong></th>
            <th><strong>test</strong></th>
            <td><strong>test</strong></td>
        </tr>
        <tr>
            <th><strong>test</strong></th>
            <th><strong>test</strong></th>
            <td><strong>test</strong></td>
        </tr>
    </tbody>
</table>
<strong>
<br />
test line beneath the table</strong>



Video reproduction in Chrome: https://www.screencast.com/t/lH3LJLKjmXb