Currently when you do right click with the mouse and by accident you move in this process the mouse a little to the direction where the pop up menu appears (consequently, by accident, you hover some action of the pop-up menu) and then you release the button, an action is triggered.
Windows, currently doesn't trigger an action when you release the mouse button, then you have to click again to select an action.

I think the current behavior in GTK+ is annoying mostly for people with some physical difficulties with the computer and for people that are not too skilled with the computer (I received complaints for both types of people).

In many cases, these people trigger an action like "Back" in the browser, "New folder" in Files, "Call" in Skype, and so on (First or last action in the pop up menu). Some of these actions are destructive, like "back" in the browser if you are writing and email, or "Call" in Skype, that by accident you can call someone that you don't want to call.

This also happens to me, so, for me it is also annoying.

To solve this, I propose to copy the Windows behavior (Doesn't trigger an action for the release of the right mouse button) or put a little timeout (comfortable time to let the person to release the mouse button) to wait until an action can be triggered releasing the right mouse button.