Lock out kmail when trying to delete text in a 25000 line email

[René J.V. Bertin]

I cannot answer your question, but this seems like a good use scenario for having a way to use an external composer on a case-by-case basis, via a dedicated action ("reply using external composer" in KMail itself, or "edit in external composer/editor" in an embedded composer window).

Alternatively, make the composer a kpart too and use a simple helper process, much like browsers like Chrome now use individual processes per page (tab, window - you can actually kill those using an internal task manager without losing your browsing session, very useful in this kind of situation when you realise the resources required for the operation you just triggered).

R.