Mouse clicks across user accounts

I have two users set up. In the realm of the second user, I activated a macro with repeated mouse clicks to keep a web page active. I switched back to the first user. The mouse clicks came through and were disrupting my work! How in the world is that possible? Mouse clicks (and almost all other activities) should never cross between users.

I have heard one other case of this happening. It should be impossible, and indicates a serious security hole in Apple's system software.

I have never been able to duplicate this, and as you say it should be impossible.

I'm using El Capitan 10.11.6. System Integrity Protection is enabled. The main user is at an admin level. The second user (with the click macro) is at a standard level.

  I tested again using a Finder window instead of a Firefox window. The problem still occurred.

  I shut down and then ran the mouse click macro on the desktop—same problem.

  I suspect that the cause is a bug in El Capitan, which was significantly different from Yosemite and had many bugs. (My big problem was folder and file permissions that El Capitan totally messed up.)

Gregory Tetrault