Control knobs emoji is not handled properly

[DrinkDregs]

Highlighting any part of a line after the character 🎛 causes the leftmost highlighted character to be partially removed, and the rest of the line shifts to the left.

In Featherpad, this character causes the cursor to become taller.

QTerminal 2.2.1

[tsujan]

Out of curiosity, I looked into it. It's one of those cases where QFontMetrics::horizontalAdvance() returns an incorrect value. A workaround is possible, but it can ruin the rendering of all other special characters.

Its rendering in Konsole is bad too — I think Konsole may have used something like the workaround I have in mind — although this problem doesn't happen there. Here is how Konsole draws four of it:

And in QTerminal:

So, I leave it as it is for now. Clean PRs that don't cause regressions are welcome.