Lowerscore on tag name bug

[TinyMCE-User]

Description of problem:
TinyMCE seems to break when you use a custom tag that contains a lowerscore.
E.g. The syntax should look like
&ltg;custom_tag>My contents&ltg;/custom_tag>

When TinyMCE renders the underlying HTML, it displays something like this:
&ltg;custom_tag>My contents

Instead of just showing the text within the tag.

Steps to reproduce:

1. Visit TinyMCE home where there is a live editor:
   http://www.tinymce.com/index.php
2. Edit the source code and paste this tag &ltg;custom_tag>My contents&ltg;/custom_tag>
3. Click the GO button and see how TinyMCE renders the HTML.
4. This only happens when there is a lowerscore in the tagname, it does not happen in any other situation, e.g. you can use mid-scores or other special characters, but the lowerscore seems the culprit.

Expected result:
It should display :
My contents

Actual result:
It displays:
&ltg;custom_tag>My contents

Legacy information imported from TinyMCE bug tracker:

#T5843 posted by TheAgux

Tags: [chrome custom tags]
Status: Open
Resolution: None
Attached URL: none

[TinyMCE-User]

I believe I found it in the TinyMCE source code, it might be good to implement it...

It is near the line with the comment

// Precompile RegExps and map objects

The "Start Element" regex has this prefix:
(?:([A-Za-z0-9-:]+)

It's a matter of adding the lowerscore to the list, like this:
(?:([A-Za-z0-9-:_]+)

It fixed it in my environment :) And I feel like a hero :)

Posted by TheAgux

[metricjs]

Hi, we've investigated this issue and cannot reproduce it in TinyMCE v4.4.0. Thanks, the TinyMCE Team.