message: move out local TODO list :-)
diff: using namespace std;
  using namespace std::placeholders;
  -/// TODO:
  -/// [ ] NEW: dpi-adjust on screen change
  -/// [ ] REVIVE: blurred background
  -/// [ ] REVIVE: numpad numbers in input mapping
  -/// [ ] QTPORT: replace FileChangeWatcher with Qt native API
  -/// [ ] QTPORT: see if it makes sense to replace Freetype/Harfbuzz with Qt's API
  -/// [ ] QTPORT: replace cerr's with GUI error dialogs / systray notification - QSystemTrayIcon::showMessage
  -/// [ ] QA: reorder function impls to match the properly ordered signatures in header file
  -/// [ ] QA: unit test: InputGenerator: char32_t 0 .. 31 equals to A-Za-z (and the others) and modifiers=Ctrl
  -/// [x] QTPORT: replace launcher() with Qt native API
  -/// [x] QTPORT: replace shortcut mapping with Qt's QKeySequence.
  -/// [x] REVIVE: keyboard input
  -/// [x] REVIVE: mouse wheel input events
  -/// [x] REVIVE: mouse move input events
  -/// [x] REVIVE: mouse click input events
  -/// [x] REVIVE: blinking cursor (missing timer)
  -/// [x] NEW: upon shell termination, print message on screen that shell has exited.
  -
  #if defined(CONTOUR_PERF_STATS)
  #define STATS_INC(name) ++(stats_. name)
  #define STATS_ZERO(name) (stats_. name = 0)
  