Personal, and Brazilian hello am new here, I'm using google traduro: P

I need help to find the mouse position in the isometric grid according to the tile, I do not know if I explained right but're there'll leave the source of my project here, since it is more to study ...
Code:
medi afire.com/download/rlye28kdu5daas5/GameEditor.rar
Here's a project the image!
Code:
i.minus.com/ilQySy3RGpvT2.png
To disable the coordinates that are on the map is only clears the option there from above!