Clicking the Browser view option in the "Coding" tab toggles a rendered web browser preview of the active file directly in the edit window. While in browser view mode, it is not possible to edit the active file. This mode is used strictly as a preview and not as a WYSIWYG editing mode.
In the Windows version of UltraEdit, browser view uses a Windows-provided Internet Explorer control to render the active file. It is not possible to change the rendering engine used for this, however you can change the IE/Edge version that is used by the rendering emulator by adding the following meta tag to the file itself:
<meta http-equiv="x-ua-compatible" content="IE=9">
This allows you to preview the file in multiple versions of Internet Explorer. For more information, see the MSDN documentation on specifying legacy document modes.
See also:
UltraEdit Wiki