Everyone who works with the Google Tag managers knows that editing code in the Custom HTML Tags for example is
very anoying. Update: There is a code highlighter available inside Google Tag Manager now! If it does not fit your needs you could fall back on the code editor mentioned in this blogpost.
Fortunately there is a Google Tag manager code editor extension for Google Chrome.
This looks like:
or Light theme
The extension is compatible with the old en new version of GTM.
There is a functionality to show the code editor full-screen and also to change the Color theme to light or Dark.
You can install it here.