Build with and for GMS 1.4. Grid path is based on a breadth first search algorithm.
scr_find_grid_path(id, target_x, target_y, diag, cell_size)
It finds the shortest way from id.x, id.y to target.x, target.y. All coordinates of the path is kept on a ds_list. Perfect for turn by turn grid based game. As always, it's well commented. Mouse click movements. YYC tested.
Cleaner code and added parentheses to statements and semicolon to all lines.