[DiapDealer]

You misunderstand. It's not that we lack the requisite knowledge of Qt to be able to do what you want. It's that we're not going to do it. You will have a much easier time of it here if you stop dwelling on what "other editors/IDEs" can do. Sigil isn't looking to mimic other full-featured editors. Heck... we're not even trying to get people to abandon their favorite editors for Sigil. That's why the "Open With" feature exists: use the editor that works best for your workflow and return to Sigil when you're done.

So you need to understand that the "other editors can..." mantra is not one that really motivates us at all. We have no desire to recreate what full-featured--but ultimately project-agnostic--code-editing IDEs already do well.