Set popup position

It could be useful to be able to set the popup position to all combinations of (top, middle, bottom) x (left, right), of the window. The default bottom-center is a bit limiting IMHO.

Personally I find it overlaps with some frequent popups like "go to type" or "go to recent files" and I'd like to avoid it.

The issue does not name any files or tests. Start by locating the popup implementation and its current bottom-center positioning, then verify how window edges and available positions are handled. Done means the popup can be placed at every top, middle, or bottom and left or right combination described, while retaining the existing default.

Written by the indexing model from the issue text.