Now, everything works fine. I added a preference for it. There will be a UI checkbox for it, but not now 
If xemmet_snippets_are_important is true, then Xemmet will check your toolbox for a snippet that called the same as the abbreviation you want to expand, and, if it will find this snippet (and it's an abbreviation, not just a snippet), then it will expand it instead of expanding an Emmet abbreviation. This is disabled by default.
To enable it for now, open Console and run this:
require('xemmet').prefs.setBool("xemmet_snippets_are_important", true). No need to restart Komodo or Xemmet.
Note
If your Emmet abbreviation is invalid (for example ~ is invalid abbreviation), then Xemmet will check if this is a custom Xemmet snippet, if not, then just pass your string to Komodo handlers, so if there's an abbreviation called "~" - Komodo will expand it; if yes, then it will try to expand it, but if it contains some errors, then Xemmet pass it to Komodo.
Note 2:
xemmet_snippets_are_important means that Komodo snippets has the biggest priority for Xemmet.
If this setting is enabled, Xemmet will parse your string in this order:
- Check if Komodo snippet, if yes - pass to Komodo to expand it, if not - next step
- Check if Xemmet snippet, if yes - expand, if an error occurred - pass it to Komodo, if not - next step
- Try to expand abbreviation, if successful - insert it, if not - pass to Komodo.
If this setting is disabled, Xemmet will parse your string in this order:
- Check if Xemmet snippet, if yes - expand, if an error occurred - pass it to Komodo, if not - next step
- Try to expand abbreviation, if successful - insert it, if not - next step
- Check if Komodo snippet, if yes - pass to Komodo to expand it, if not - do nothing.
