Steps to reproduce (this occurs on iOS, not on Android)
1. Go to beta labs and log in
1. Make sure you have "Enable editor help panel" set in preferences
1. Login on an iOS device
1. Make sure you are in visual edit mode
1. Open the help panel
1. Tap into the textarea. It will be covered up by the keyboard
1. Switch to source edit mode, open the help panel, tap in the textarea, all looks fine
See also the short video below:
{F27825373}
Note that the video is taken on a local site with https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/482822 applied; the behavior without this patch is even more broken as iOS Safari thinks there two text inputs (the VE surface, and the process dialog text area). The patch partially fixes the problem by detaching the VE overlay, but the textarea not coming into view is still a problem.
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Not removing the MobileFrontend Overlay and then moving the help panel window manager inside the MobileFrontend overlay (see below) seems to partially fix the problem:
{F27825608}
However the second text input (for the VE surface) is still presented to iOS. But this indicates that the styles used for MobileFrontend Overlay can probably fix the problem we're seeing with our help panel overlay/window manager.