Provide visual debugging for MouseArea and TouchArea

I am hitting constant issues with daft uses of MouseAreas. Is there a good reason why we cannot have a debug mode where MouseArea and TouchAreas become semi transparent rectangles that can be seen? Semi transparent so you can also see where multiple ones overlap. This would help us solve no doubt hundreds of stupid usability problems that exist due to silly things you can do with an item you cannot see.

Enabling via an environment variable, e.g. QML_VISUAL_TOUCH_DEBUGGING=1