Sometimes, after entering in a backslash, a dialog "Press ENTER to surround previous selection with selected commamd" will show.
\documentclass, then use TAB to auto-complete it as \documentclass{<class>}.<class>, then something unexpected will show at the top of editor.The backslash \ should be normally typed in.

VS code: version 1.17.0
LaTeX-Workshop: version 3.5.5
This works as intended. When there is a selection, backslash will try to surround the selected content with LaTeX commands. You may remove the selection with backspace and then \ to insert command.
I know this is somehow misleading. However, I cannot come up with a better invoke method for the command surrounding feature.
_Can you think of another way to invoke this or provide us with a setting to disable this feature?_
Personally, I don't use it at all, but find myself replacing text via selection very often. Thus, the quick selection pops up and everytime this happens I'm forced to press ESC to hide it.
Currently I just edited command.js in out\src\providers\completer to remove this feature entirely.
I would figure this as a reasonable feature request. Will do soon.
Thanks for implementing this. Could you possibly add a similar option for autocompletion of $'s for math mode, braces, etc?
That is not possible with the current vscode API. They are implemented using a different pattern than command completion. The said completion is actually named pairing.
Thanks for this option!
Thank you!
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Thanks for this option!