Fix cases where widget interaction did not update item values.

Also, properly avoid updating the item during interaction (drag)
events and properly signal modification to parent view.
29 jobs for !2301 with missing-updates in 2 minutes and 5 seconds (queued for 4 seconds)
detached
Status Name Job ID Coverage
  Build
canceled build:fedora31 #5187234
build cmb docker linux

00:02:04

canceled build:fedora31-asan #5187239
build cmb docker linux

00:02:02

canceled build:fedora31-coverage #5187242
build cmb docker linux

00:02:01

canceled build:fedora31-nodata #5187237
build cmb docker linux

00:02:04

canceled build:fedora31-paraview #5187236
build cmb docker linux

00:02:04

canceled build:fedora31-tidy #5187241
build cmb docker linux

00:02:02

canceled build:fedora31-ubsan #5187240
build cmb docker linux

00:02:02

canceled build:fedora31-vtk #5187235
build cmb docker linux

00:02:04

passed build:fedora31-vtk-python2 #5187238
build cmb docker linux

00:01:58

 
  Test
canceled test:fedora31 #5187243
cmb docker linux x11

canceled test:fedora31-asan #5187248
linux privileged x11 cmb docker

canceled test:fedora31-coverage #5187250
cmb docker linux x11

canceled test:fedora31-nodata #5187246
cmb docker linux x11

canceled test:fedora31-paraview #5187245
cmb docker linux x11

canceled test:fedora31-ubsan #5187249
cmb docker linux privileged x11

canceled test:fedora31-vtk #5187244
cmb docker linux x11

canceled test:fedora31-vtk-python2 #5187247
cmb docker linux x11

 
  Analyze
canceled analyze:fedora31-coverage #5187251
build cmb docker linux

 
  External
passed cdash-buildbot

passed cdash-private

passed cdash-public

failed ghostflow-branch-check-master

canceled smtk@master-moho-linux-shared-relwithdebinfo+examples+private+remus

00:00:45

canceled smtk@master-norkit-osx-shared-release+examples+matplotlib

canceled smtk@master-praxis-windows-shared-release

00:00:45

canceled smtk@master-talosiv-osx-shared-release+examples+matplotlib

00:00:45

canceled smtk@master-tatooine-osx-shared-release+examples+matplotlib

00:00:06

canceled smtk@master-tatooine-osx-shared-release+examples+matplotlib+private

00:00:45

passed cdash-buildbot