Searching in PDF causes weird bugs

[d125q]

VimFx version: 0.20.3
Firefox version: 49.0.2
OS: 64-bit GNU/Linux
Keyboard language: us
Example URL (if any): http://infolab.stanford.edu/~ullman/ialc/spr10/slides/rs2.pdf

Steps to reproduce:

1. Open http://infolab.stanford.edu/~ullman/ialc/spr10/slides/rs2.pdf
2. Open the search bar by pressing /, then type a search string such as int
3. Press n a few times.

Expected result: VimFx continues searching.

Actual result: VimFx stops searching. Furthermore, VimFx stops working completely on all other tabs. In order to make it work again, you have to go back to the PDF, press Esc to exit from the Find mode, then press / again, then exit normally again.

Note that this is not limited to the PDF given above.

[aleprovencio]

Yes, I can confirm that also.