I have the solution all you young gani g0ds need. It's time to cut that sprite selection and indexing time down to zero and make the offline editor great again.
Grab the repo & Visual Studio to build it yourself or the latest release.
Not going to address any OS X issues because the offline editor doesn't work there to begin with although you can compile it on your own if you really wanted.
Demo:
GitHub Repo: https://github.com/cesoun/QuickSprite
Releases: https://github.com/cesoun/QuickSprite/releases
Found a bug? Want a feature? Let me know: https://github.com/cesoun/QuickSprite/issues
Update: 6/9/2018
Precision Slider & Intersect Merging.
These changes help support better sprite selection and definitions. Now QuickSprite will attempt to merge intersecting sprite definitions. These are usually close enough to be part of a single sprite anyways and it does a fairly good job. Only issue being that smaller sprites get left out sooner because of it. (Ex. 1x1 / 2x2) The Precision Slider lets you adjust the min-max of your sprites to give the merging function a chance to grab everything.