mir_demo_server steals drag gestures from the client

[Daniel van Vugt]

mir_demo_server steals drag gestures from the client.

Test case:
 1. mir_demo_server &
 2. mir_demo_client_fingerpaint
 3. Draw by dragging the mouse around.
 4. Drag up past the top of the window and down again.

Expected: fingerpaint keeps painting (as it does for the other edges)
Observed: mir_demo_server steals the drag gesture from the client and moves the window instead.

Also try with a windowed client like mir_demo_client_egltriangle.

[Daniel van Vugt (vanvugt)]

Note that Mir's input/gesture targeting code is designed to avoid these problems, by sending input events only to the surface where the gesture began. But I'm guessing mir_demo_server doesn't use that existing window stack logic.

[Michał Sawicz (saviq)]

Syncing task from Mir.