Make form opaque on mouse hover

Hey all

I have a Windows Form which is always on screen in the corner and cannot be closed by the user. Depending on circumstances, the form may be on top of the exit, minimise and maximise buttons, therefore obstructing them. What I want to do is when the user hovers their cursor over the form, I would like the form to become opaque (opacity of 35) so that what's behind the form can be seen and be interacted with. Then when the user moves the cursor off the form, it returns to it's original non-opaque state.

Could anyone provide any code which would make this possible?

Cheers