When editing certain HTML layouts in a RadEditor on a Mac, when you right-click on the empty space to the right of the text content in a table cell inside a nested table, then click Row -> Insert Row Above, the editor inserts a row above the current row in one of the parent tables, instead of in the table containing the specific cell that was clicked on.
To reproduce, paste the following code into the HTML view of a RadEditor. Then switch to Design mode, and right click in the empty space to the right of the text "Type your message here!", but within the same table cell as that text. Select Row -> Insert Row Above, and see that the editor inserts a row into the wrong table.
This is only reproducible on a Mac, but it has been confirmed to happen in both Safari and Chrome.
The project this is for is currently using version 2016.3.1027, however I've pasted this code into the Telerik RadEditor demo at https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx , which I presume is running the latest version, and the problem is reproducible there also.
<!DOCTYPE html>
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
<meta content="width=device-width" name="viewport" />
<title>Newsletter from your Pro</title>
<style type="text/css">
<!--
-->
</style>
</head>
<body>
<table style="background-color: #C9CAC8 ;" cellspacing="0" cellpadding="0" border="0" width="100%">
<tbody>
<tr>
<td>
<table style="border-collapse: collapse; mso-table-lspace: 0pt; mso-table-rspace: 0pt; font-family: Gotham, 'Helvetica Neue', Helvetica, Arial, sans-serif;" class="body" cellspacing="0" cellpadding="0" align="center" border="0" width="640">
<tbody>
<tr>
<td style="background-color: #ffffff; height: 60px;" class="side-pad" colspan="6" align="center"><span style="text-align: center;" class="devicewidthinner"></span></td>
<td style="background-color: #ffffff; height: 60px;" class="side-pad" align="center"><span style="font-size: 14px; font-family: Helvetica, Arial, sans-serif; color: #63666a;">February 5, 2019</span></td>
</tr>
<tr>
<td style="background-color: #ffffff; height: 87px;" class="side-pad" colspan="6" align="center"><span class="devicewidth"></span></td>
<td style="background-color: #ffffff;" class="side-pad" align="center"></td>
</tr>
<tr>
<td style="background-color: #d55c19; width: 201px; height: 30px;" class="side-pad" align="center"><span style="text-align: center; font-weight: normal; line-height: 24px; font-family: Helvetica, Arial, sans-serif; font-size: 13px; color: #ffffff;"><a style="color: #fff; text-decoration: none;" href="http://www.test.com">Visit website</a></span></td>
<td style="background-color: #ffffff; width: 4px;" class="side-pad" align="center"> </td>
<td style="background-color: #d55c19; width: 86px;" class="side-pad" align="center"><span style="font-family: Helvetica, Arial, sans-serif; font-size: 13px; color: #ffffff;"><a style="color: #fff; text-decoration: none;" href="mailto:test@test.com">Email me!</a></span></td>
<td style="background-color: #ffffff; width: 4px;" class="side-pad" align="center"> </td>
<td style="background-color: #d55c19; width: 122px;" class="side-pad" align="center"><span style="text-align: center; line-height: 15px; font-family: Helvetica, Arial, sans-serif; font-size: 13px; color: #ffffff;">123-456-7890</span></td>
<td style="background-color: #ffffff; width: 4px;" class="side-pad" align="center"> </td>
<td style="background-color: #63666a; width: 201px; height: 30px;" class="side-pad" align="center"><span style="text-align: center; font-weight: normal; font-size: 12pt; line-height: 24px; font-family: Helvetica, Arial, sans-serif; color: #ffffff;">Test Testerson</span></td>
</tr>
<tr>
<td style="background-color: #ffffff;" class="side-pad" colspan="7" align="center">
<table class="container" cellspacing="0" cellpadding="0" align="center" border="0" width="600">
<tbody>
<tr>
<td style="height: 250px;" align="center">
<table class="row" cellspacing="0" cellpadding="0" align="center" border="0" width="580">
<tbody>
<tr>
<td style="height: 250px;">
<table cellspacing="0" cellpadding="0" border="0" width="100%">
<tbody>
<tr>
<td style="width: 100%; height: 205px;" valign="top">
<table style="mso-table-lspace:0;mso-table-rspace:0;" cellspacing="0" cellpadding="0" align="left" border="0" width="100%">
<tbody>
<tr>
<td style="font-size: 14px; color: #63666a; font-weight: normal; line-height: 20px; width: 205px;" colspan="4" valign="top"> </td>
</tr>
<tr>
<td style="font-size:14px; color:#63666a; font-weight:normal; text-align:left; line-height:20px;" colspan="4" valign="top"><span style="font-size: 14px; font-family: Helvetica, Arial, sans-serif; color: #63666a;">Type your message here!</span></td>
</tr>
<tr>
<td style="font-size:14px; color:#63666a; font-weight:normal; text-align:left; line-height:20px;" colspan="4" valign="top"> </td>
</tr>
<tr>
<td style="font-size:14px; color:#63666a; font-weight:normal; text-align:left; line-height:20px;" colspan="4" valign="top"> </td>
</tr>
<tr>
<td style="font-family: Helvetica, Arial, sans-serif; font-weight: normal; font-size:14px; color: #63666a; line-height:18px; text-align:left;" colspan="4">
<p> </p>
</td>
</tr>
<tr>
<td colspan="4" valign="top"> </td>
</tr>
<tr>
<td colspan="4" valign="top"> </td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr>
<td style="background-color: #63666a;" class="side-pad" colspan="7" align="center">
<table class="container" cellspacing="0" cellpadding="0" align="center" border="0" width="600">
<tbody>
<tr>
<td align="center">
<table class="row" cellspacing="0" cellpadding="0" align="center" border="0" width="580">
<tbody>
<tr>
<td>
<table cellspacing="0" cellpadding="0" border="0" width="100%">
<tbody>
<tr bgcolor="#63666A">
<td style="height: 18px;" valign="top" align="center"> </td>
</tr>
<tr>
<td valign="top">
<table style="mso-table-lspace:0;mso-table-rspace:0;" class="full-width collapse" cellspacing="0" cellpadding="0" align="left" border="0" width="100%">
<tbody>
<tr>
<td style="font-size:12px; color:#63666a; font-weight:normal; text-align:left;" class="center">
<p><span style="font-size: 12px; line-height: 14px; text-align: left; font-family: Helvetica, Arial, sans-serif; color: #ffffff;" class="footer">Here is some footer text.</span></p>
</td>
</tr>
</tbody>
<tbody>
<tr>
<td class="center" valign="top" align="center"> </td>
</tr>
<tr>
<td class="center" valign="top" align="center">
<table cellspacing="0" cellpadding="0" align="center" border="0">
<tbody>
<tr>
<td align="center"></td>
<td style="width: 12px;" align="center"> </td>
<td align="center"></td>
<td style="width: 12px;" align="center"> </td>
<td align="center"></td>
<td style="width: 12px;" align="center"> </td>
<td align="center"></td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
<tr style="background-color: #636666a;">
<td style="background-color: #63666a;" class="side-pad" colspan="7" align="center">
<table class="container" cellspacing="0" cellpadding="0" align="center" border="0" width="600">
<tbody>
<tr>
<td align="center">
<table class="row" cellspacing="0" cellpadding="0" align="center" border="0" width="580">
<tbody>
<tr>
<td style="height: 20px;"> </td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
<p> </p>
</td>
</tr>
</tbody>
</table>
</body>
</html>