terminate called after throwing ...Whoops, I misunderstand how Mir pointer events work

[Alan Griffiths]

Running a wayland client in miral-app...

Specifically:

QT_QPA_PLATFORM=wayland /usr/lib/x86_64-linux-gnu/qt5/examples/webkitqml/flickrview/flickrview

While attempting to scroll though the ribbon at the bottom I got:

terminate called after throwing an instance of 'std::logic_error'
  what(): Whoops, I misunderstand how Mir pointer events work
Aborted (core dumped)

This appears to come from calc_button_difference() in src/server/frontend/wayland/wayland_connector.cpp

Sadly, I didn't get a core as I had an old one. But we don't want servers crashing this easily.

[Alan Griffiths (alan-griffiths)]

A bit more info from adding

        sprintf(buffer, "Whoops, I misunderstand how Mir pointer events work. old=0x%02x, updated=0x%02x", old, updated);

I can generate this error with the following errors:

Whoops, I misunderstand how Mir pointer events work. old=0x00, updated=0x00
Whoops, I misunderstand how Mir pointer events work. old=0x00, updated=0x20
Whoops, I misunderstand how Mir pointer events work. old=0x00, updated=0x40
Whoops, I misunderstand how Mir pointer events work. old=0x01, updated=0x01
Whoops, I misunderstand how Mir pointer events work. old=0x01, updated=0x02
Whoops, I misunderstand how Mir pointer events work. old=0x01, updated=0x20
Whoops, I misunderstand how Mir pointer events work. old=0x07, updated=0x00
Whoops, I misunderstand how Mir pointer events work. old=0x07, updated=0x01

The specific case that in the bug description is to press the primary button, move the pointer out of the Mir-on-X window, release the button move the pointer back into the window and press the button again.

[Mir CI Bot (mir-ci-bot)]

Fix committed into lp:mir at revision None, scheduled for release in mir, milestone 1.0.0