1. Create an input.
2. Create a button on top of it
3. Try to click the button.

Will not work, the focus goes to the input and the button click is ignored.

Included pics to demonstrate.
In the pics you can see that when the cursor is on a button half, that is not on an input, the focus goes to the button. And when the cursor is on a button half, on top of the input, the focus goes to the input.

Capture.JPG Capture2.JPG