Need WPF support

I want to create a WPF grid where users can drag controls from one cell to another, and when the user drags, I need to draw tooltips on the screen like arrows. As if the clues were in ANOTHER LAYER on the screen. That is, they are not drawn in the grid I mentioned.

The problem is this: I don't know how to OVERLAP a "transparent" canvas on top of my grid so that I can draw on it.

Do you have guys who have a hint? THANKS.