OBS:
If Arma is started in windowed mode, and focus is switched to another program while Arma is loading, Arma3.exe enters a "half focused" state, where it is not in focus as far as Windows is concerned (Arma is not displayed on screen), but it plays sounds and catch HID actions as if it were in focus. This results in mouse clicks and key presses in other programs affecting both that other program and Arma.
For example, pressing spacebar while typing in Notepad can result in Arma opening the News Dev Log link, or clicking a link in web browser resulting in starting missions through the menu.
When in this state, the user could inadvertently perform undesired actions in Arma, such as reverting a campaign or deleting the user profile.

EXP:
Arma should only catch key presses and mouse clicks if it is in focus, and do nothing if it is not in focus.