Page turner progress bar should move leftward for RTL books

[nathangibson]

Description

(With much appreciation to @Pyrojet99 , @iisa, and others I don't know of who have worked to make RTL reading a good experience! ... ) Although the arrow buttons, arrow keys, and page turning animation all match the reading direction for right-to-left books, the progress bar on the bottom does not. It moves rightward as the reader progresses through the book leftward.

Evidence / Screenshot (if possible)

From https://archive.org/details/gendaitankashu00meijuoft/page/27/mode/2up

Expectation

For RTL books,

• the progress bar should begin on the right for page 1 and move leftward as page numbers increase
• dragging the progress bar handle leftward should increase the page numbers, rightward should decrease them
• clicking to the left of the progress bar handle should jump to a later page, clicking to its right should jump to an earlier page

Context

FF 84.0 on Mac 10.14.6

Proposal & Constraints

?

Stakeholders

@right2leftdh

[VallariAg]

@iisa @cdrini @Pyrojet99 Can I work on this?

[Zaidtech]

Can i work on this issue?

[nathangibson]

Thank you @VallariAg (and @Zaidtech)! I'm hoping your fix goes into production and am looking forward to a better RTL experience :-)