Mike Fleetwood authored Apr 10, 2019 and Curtis Gedak committed Apr 11, 2019

Having a member variable named 't' which is used to share state in a
Dialog_Progress object between on_signal_show() and on_cancel() methods
is horrible.  Rename to something more meaningful.

Also initialise m_curr_op in the constructor's initialisation list,
rather than later when first used in on_signal_show().  Not strictly
required, but avoids this POD (Plain Old Data) member variable being
undefined in the Dialog_Progress object between construction and when
on_signal_show() previously assigned to it for the first time and
started using it.

* C++ FAQ / Should my constructors use "initialization lists" or
  "assignment"?
  https://isocpp.org/wiki/faq/ctors#init-lists