Dialog: Focus management should honor isDefaultPrevented

[benshu]

Scenario

• The last tabbable element within a dialog has the focus.
• The user presses the tab key.

Behavior:

1. The dialog registers the keydown event of the tab key.
2. The dialog moves the focus to the first tabbable element of the dialog.

Currently there is no way to prevent the described bahavior. If an independent listener ​tries to move the focus somewhere else, it is "overriden" by jQuery UI dialog. Because the dialog widget moves the focus with a delay of 1ms there is no reasonable workaround.

I contend that isDefaultPrevented() should be checked and that the focus should only be moved if it returns false.

FYI, the ​fix for #9646 is broken. Shift-tabbing from the first to the last element no longer works. The focus will remain on the first element.

[Scott González]

I agree with this proposal. The shift-tab behavior is a simple fix as well, looks like it was a copy/paste error.

[Jörn Zaefferer]

PR for the shift-tab issue: ​https://github.com/jquery/jquery-ui/pull/1264

[Jörn Zaefferer]

Dialog: Fix shift-tab handling, focus the correct element

Copy-paste error introduced in df6110c0d424ff3306fdd5576011f2dcf4d242d0

Updates the tabbing test to be more specific about which element should have focus, instead of only checking if focus is within the dialog.

Ref #9646 Ref #10103 Closes gh-1264

Changeset: a0b84767a76098cdcc6375dfe28a7fee866bd395

[Jörn Zaefferer]

Dialog: Honor preventDefault when managing focus

If event.isDefaultPrevented() is true, the focus management is completely skipped, assuming the user manages focus manually.

Fixes #10103 Closes gh-1265

Changeset: 226cc3e9e57c7591ff6a2ee02ffed52ac97786a9