18f6ab1 changed the behavior when resizing floating clients using the
mouse (via modkey + RMB).
Previously, you could initiate the mousegrabber using e.g. "modkey +
RMB", release the key and button, and resize the window using the left
mouse button.
This restores this behavior by canceling the mousegrabbers only if the
cursor was moved, without _any_ mouse button being pressed.
Fixes https://github.com/awesomeWM/awesome/issues/309.
Closes https://github.com/awesomeWM/awesome/pull/310.
Daniel Hahler
actionless
Julian Wollrath