https://addons.mozilla.org/en-US/firefox/addon/mua-web-unicode-converter/

Copy/Paste Khmer Unicode into here as there is a few more things : https://addons.mozilla.org/en-US/firefox/extensions/

Please let us know if this solved your issue or if need further assistance.

Is this about typing Khmer text in a textarea or about showing the Khmer glyphs?

If this is about the latter then what do you see instead?

Can you attach a screenshot?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot

You can also check for sandbox issues, see:

• https://wiki.mozilla.org/Security/Sandbox