This can be difficult to ask because 1) people assume this is necessarily malicious and 2) unrelated but effectual techniques like GetForegroundWindow can make this impossible to answer.
So, to keep this as general as possible: If I wish to send keyboard and mouse events to a program but it is ignoring messages other programs receive and interpret just fine, what might I try? What might the developers be trying? The goal is to have multiple windows receiving input at once.
My specific case is that I wish to be doing things on my system while the target window receives clicks and keyboard input at a set interval. I could just toggle foreground, but I really don't want to.
If this would better fit somewhere else than reverseengineering or if some variation on this has already been asked I would, of course, be perfectly content to respectively post elsewhere or read said variation.