[oneeyedpigeon]

It's actually surprising to me that the behaviour you describes works as it does. I would expect the first click to focus the window, then a second click to be required to open the menu. Does that mean that, if you want to focus a window, you have to find 'dead space' to click on if you don't want some other side effect?

[banana_giraffe]

yes, on either MacOS or Windows, if you click on an area in a window that doesn't have focus that triggers some action, that action will be triggered.

There are exceptions on both platforms, games being common because of how they grab input.

I've long since gotten in the habit of using the title bar or window-resizing area to safely activate a window .. when I'm using the mouse to change focus.

[digisign]

Get ready to have your mind blown because a used-to-be common setup on the X Window system is to be able to fully interact with a window without having to bring it to the foreground. Great for terminals and a few other use cases. I still use it.