Edit Page: Upload button to insert Image/Video does not received keyboard focus and additionally the focus moves in background.

Issue Description

After activating the Insert Images and files link in the toolbar section for the edit page, a modal appears to select the files, but the focus moves inappropriately to the background instead of the modal and focus is not available on the "Upload file" button.

URL to the Page

https://instenv-16545-au0r.instenv.internal.atlassian.com/pages/resumedraft.action?draftId=2228236&draftShareId=a6012b1c-24e8-4c73-9ac8-566af099b4a7&

Platform: Confluence server

Version: 7.17.0

Steps to Reproduce

1. Launch URL
2. Navigate to the "Insert Files and images" link in the toolbar section in the main content area and activate it.
3. Navigate in the available modal to the "Upload files" button.

Screen Recording

Screen Recording 2022-04-12 at 1.35.07 PM.mov

Actual Behaviour

For the media insertion modal dialog containing "Upload Files" button do not receive keyboard focus. When the modal dialog is displayed on the screen, the keyboard focus moves on the background content and on the other elements in the modal except "Upload files". This make the keyboard user as well as assistive technology user unaware about the available content.

Expected Result

Ensure that the keyboard focus moves at the beginning of the modal dialog content when the modal dialog gets displayed on the screen. All the interactive elements should receive keyboard focus. This will make the user aware of the content and able to use the function with keyboard.

AXQA Ref:AXQA-371