Correcting in-built PDF's highlighting

[ReFlash]

Recent version's of Firefox have implemented a much needed feature of highlighting a PDF's text. Yet, it's implementation leaves room for accessibility problems (view attachment).

When fitting the pdf to my monitor's width while highlighting things, too often I have to move the page up or down, distracting me from reading. I suggest that this should be fixed, by creating a more flexible UI for this, either by implementing the highlighting functions in a secundary menu with right click on the mouse (like MSedge), by creating a floating panel that could be reduced and dragged or moving the panel of the options where the highlighting is to the right vertical position, or even something more creative - I just think that as it is, it's not suitable for people who like to or need to highlight a lot.