Follow-up: I got inspired to (re)read a few technical reports about security in windowing systems, and found that EROS' window system EWS [1] uses a variation o

Follow-up: I got inspired to (re)read a few technical reports about security in windowing systems, and found that EROS' window system EWS [1] uses a variation of this method: A "Paste" widget is overlaid with a special transparent window which when clicked authorises access to the clipboard while forwarding the click. Abuse of the mechanism is supposed to be controlled by the transparent window setting the mouse pointer to a specific shape when hovering over it: a user would be alerted if he sees that shape where it isn't supposed to be. [1] <http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.133.2919 http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.133....>