problematic positioning with multiple windows

[moberer]

Simplest way to reproduce:
Open a source file, open treemacs, hover over a function.

When hovering over a function in the left window, the box appears on the top-right. (Which is expected)
When hovering over a function in the right window, the box appears on the top-left.
This is - as far as I can tell from the source code - intentional.

Firstly, the objective problem with this:
While using e.g. treemacs or neotree, they put a small frame on the left side of the window.
Because these frames are so narrow, the displayed eldoc-box 'spills over' into the main window and hides significant amounts of code.
This means one is pretty much unable to edit the first ~15 lines of any source file.

Since I always have treemacs open, this led me to assume this package was completely broken when I first used it.
Only after reading and trying to understand the source-code, I could understand what was going on. (Since this behavior isn't really documented).

Secondly, a more subjective point:
While the current behavior is well-intentioned, I think there is also some value to be found in placing the box always in the same position. This way the user knows where to expect it, and doesn't have to 'hunt it down' with their eyes every time.

For my personal purposesI have made an adaption to the existing eldoc-box--default-upper-corner-position-function, making it always display in the top right corner:

(defun eldoc-box--default-upper-right-corner-position-function (width _)
  (pcase-let ((`(,offset-l ,offset-r ,offset-t) eldoc-box-offset))
    (cons (- (frame-outer-width (selected-frame)) width offset-r)
               offset-t)))

My suggestion would be to make this behavior the default, as it is much less likely to frustrate or confuse new users.
The currently-default behavior could be made an opt-in to those users, who still like it.

[casouri]

Thanks. And sorry for the delay. Fixing the box at top-right will block the right window for those who uses two side-by-side windows. So I don't think it is a strict improvement of the current default. I'll think of a smarter way of positioning the box.