Feature or bug - diagnostic window always moves the focus to the popup

When I hover over a diagostic, the popup appears AND sets the focus therein. The fix is easy enough…

-- Popup when hover
autocmd("CursorHold", {
    pattern = "*",
    callback = function() vim.diagnostic.open_float(nil, { focusable = true }) end,

However, there are often times when I want to copy the message to retrieve information about it using google or the like. The ability to select and copy the message is lost when focusable = false.

What would be best in my use case would be to have the popup occur without it taking focus. That instead, if I want focus on the popup message (dare I say :))), I would use the mouse given the popup is not a buffer (thus outside by ability to select using keybindings).

The question: In designing the float’s behavior, should the default use of open_float become the focus, or should it maintain the focus in the parent buffer?