Thanks for your reply! I investigated the code of Custom Buttons more deeply, and you are right, the Custom Buttons extension solely relies on the platformVersion, Since you removed the XUL stuff, you logically can't keep the platformVersion at 68. But your new release Mypal 68.14.8b has become somehow versionless. It doesn't behave as a Firefox 68 and it doesn't behave as a Firefox 74. It's a bit lost. Your browser tells Custom Buttons that it is Firefox 74, but it is not. Today, for this purpose, I have made a proof and installed Firefox 74 Portable on a Windows 7 Professional 64-Bit notebook, injected the two files config-prefs.js and config.js, and installed the legacy Custom Buttons extension. As I have already predicted, Custom Buttons runs perfectly under Firefox 74. The code editor is fully functional. The legacy Custom Buttons extension has always been compatible with much newer Firefox versions and is constantly being developed further. Here are two screenshots to demonstrate what the issue is about:
Custom Buttons' broken code editor in Mypal 68.14.8b:
Custom Buttons' fully functional code editor in Firefox 74.0.1:
As I already said, you must have removed something that Mozilla did not. And I suspect it has something to do with XBL. Certain functions for binding XML files are required by the Custom Buttons extension for the code editor, which you have probably removed. That's why I said your new release is somehow versionless. Neither fish nor fowl. Sorry for that! The conversion from XUL to XHTML is no problem as you can see. Anyway! I hope you won't behave worse than Mozilla did in the past, and I urgently hope you will be able to restore a general version compatibility. And it doesn't matter which Firefox version you raise the platformVersion to as nevertheless the Custom Buttons extension should work then.