This could maybe work better:
On object touch/collision/overlapping:
System -> Compare two values (touch.x < object.x + (object.Width / 2))
System -> Compare two values (touch.x > object.x - (object.Width / 2))
---Object -> Simulate control -> Left
Difference being, LittleStain's code would work if you clicked to the left of the object, not actually clicking the left side of the object if the .x wasn't measured from the middle, for example, if you had shifted the default image point. LittleStain please correct me if I'm wrong but I thought X and Y were measured from the left edge of the object.