This would make the GUI tool for adding TemplateData to templates compatible with gadgets and user scripts such as the popular WikEd. Currently, the data is not saved if the gadget is enabled, as reported at
|mediawiki/extensions/TemplateData : master||Use textSelection API to modify textarea|
WikEd is not an extension hence this is unfortunately out of scope for Bugzilla.
Closing as INVALID as this is not a bug in MediaWiki software or its extension, but in an on-wiki script/gadget.
though it's going to be worth reviewing that in the light of Phabricator
The issue tracking tool feels rather unrelated; a central hosting for gadgets is rather what I consider to be needed first.
Part of the problem reported on this task is TemplateData's fault, which should be using the default module "jquery.textSelection" for interaction with the textarea instead of these custom methods:
(this is what is done by CodeEditor, CodeMirror and gadgets/users scripts in general)
I think this task can be re-purposed for implementing that, so I'm reopening it.