Lightbox Keyboard Support

[crhallberg]

• Constrain keyboard focus to lightbox.
• Add ESC to close lightbox.

[ckaz]

You are amazing! Will look at this tomorrow. Good night!

[ckaz]

Just tested this -- works like a charm! Thanks!
Just wondered whether it would be more accessible if we hid the "icon" in the close button like so:
<button type="button" class="close" data-dismiss="modal" aria-label="<?=$this->transEsc('Close modal') ?>"><i class="fa fa-times" aria-hidden="true"></i></button>

[demiankatz]

@crhallberg / @ckaz: this PR has some conflicts that need to be resolved. I'm curious if it's still worth the effort of backporting this to release-5.1 and then merging it all the way forward, or if we can just move development to the bleeding edge. If having it in release-5.1 would help @ckaz, I'm certainly willing to continue that approach, but since 6.1.2 has now been released, I'm not expecting any further 6.x releases unless a major bug is discovered, so it may be better to refocus on new development. Thoughts/opinions?

[crhallberg]

I'd be happy to resolve as far back as would be useful for @ckaz.

[ckaz]

Sorry for taking so long. I was on vacation. Please don't put too much effort into backporting this. I could easily create a working version in our standard theme and take it from there!

[demiankatz]

Thanks, @ckaz; @crhallberg, can you re-target this against the dev branch and resolve any outstanding conflicts?

[demiankatz]

@crhallberg, thanks for the progress on this. I noticed that it was still based against the release-5.1 branch; I've changed it to use dev as the base branch, which required me to recompile the LESS to resolve conflicts. Do you mind giving this one more review to be sure I haven't messed anything up?

[demiankatz]

@crhallberg, I notice that there seem to be some Javascript style issues that are preventing the build from passing here... Can you fix?

[demiankatz]

All tests are passing; merging now! Thanks, everyone.