Checkmarks can be edited while in Presentation mode

[bogdanmaris]

Affected versions

• 81.0a1 (2020-08-17)

Affected platforms

• Windows 10
• macOS 10.15
• Ubuntu 18.04 64bit

Steps to reproduce
pdfjs.renderInteractiveForms - true

1. Launch Firefox
2. Access a PDF form with fillable content (eg: https://www.irs.gov/pub/irs-pdf/f1040.pdf)
3. Enter presentation mode
4. Scroll to page 2 and try and fill the form

Expected result

• Form can't be edited since we are in presentation mode.

Actual result

• Checkmarks can still be edited while in presentation mode.

Additional notes

• S3 as suggested severity, not sure how many people use presentation mode
• Not sure if this is intended behavior or not though

[timvandermeij]

This most likely applies to all form fields, not only checkboxes.

[Snuffleupagus]

This is probably more complicated than it first looks, since a CSS-only solution won't prevent all editing in PresentationMode.
For example: While you can use pointer-events: none; to prevent clicks, that won't help if the user uses Tab to navigate.

Basically, I think that what we'll need to do is disable renderInteractiveForms while PresentationMode is active. While making this change would be easy, it'd cause any data that the user has already entered on the page to not be displayed while PresentationMode is active, this might be unexpected and/or outright bad UX!?
Obviously we could fix that as well, by adopting a similar approach as used when e.g. printing, however it might become a bit messy given how the code is currently structured.