Stage 3 - The Code
For our event sheet, there are only a few events needed. Ones indicated with (*) are optional bits of code (addons if you like).
The select sprite
Handling the placing of the placed sprite
Making sure we dont spawn 1 sprite over another (*)
We then need to change the collision with the placed tile to be -1 away from each side, for example my image is 128x128 so my collisions would be Left - 127, Right - 127, Top - 127, Bottom - 127. Hopefully the screenshot helps explain this.