AmigaOS style single LMB click

For AmigaOS standard effect of single LMB click on a window was just (and only) activating of the window. The window was not bring to front. Bringing to front could be achieved by pressing Dept gadget; some programs (called Commodities) was able to assign double LMB click the role.

For Windows an activated window is automatically bring to front. Sometimes I am trying to perform drag&drop and once I have selected some elements of source windows the window is bring to front and obscures destination window.

Is there some Windows program that can change the effect of single LMB on a window, so that the window is not automatically bring to front?

maybe that is what you need

Sounds like a job for Autohotkey. Activating a window without bringing it to front might be very tricky tho, because that behavior is ingrained into Windows, regardless of whether you clicked on it or not.
However, you could set the active window on-top and activate the window under mouse, which would kinda do what you'd want, but then you'd have to un-not-on-top previous active window again somehow. Maybe somebody else has a better idea.

EDIT: apparently some other people had the same idea and possibly solved it:

EDIT2: Another thread

I do not want to activate a window without clicking on it (effect of X-mouse). I want to single click on a window and achieve an effect that the window is activated but is not bring to front. And then to bring the window to front I need to make something else (e.g. double click on the window).

I will try to read information on AutoHotkey forum. Thanks for links.

EDIT: "I do want" -> "I do not want"