First of all, hi!
I'm new to this engine, but have been using GMS for some time. I searched for a couple of days, and have not found my answer anywhere on the internet.
My goal is to rotate the camera with the player, who's walking in a top-down-shooter style [eg. Robotron2084]. I want the player to appear stationary relative to camera.
So in a sense use lookat() to follow the mouse pointer. I can do it with buttons, like A and D to rotate a camera. But that's not the point. I also tried using calculated angles to add or subtract to the player and camera rotation (based on getlastmousespeed < or > 0). But it was really glitchy, I must have been doing something wrong.
Here's my scene hierarchy. The camera follows the player via the script.

Here's my poor visual representation, I apologise for the bad photoshop. I hope it helps.

I probably missed some vital detail, if I did please let me know. Thanks in advance! :)