In bug 1115290 we found that, on TV layout, when the keyboard is shown, an unnecessary 1px blank line presents between keyboard and app window. As a result the background app window under the foreground app is visible at this thin and long area. We made a workaround on it[1] but we need to find the root cause. [1]https://github.com/mozilla-b2g/gaia/pull/27587/files#diff-5758423742a6b5265057da477080afaaR222

We've discussed with John Lu and made some survey. Currenly we haven't found root cause yet. Rudy do you have any idea on this issue?

Some addendum from offline discussion: That thin "line" is *not* a result of dpx-rounding calculation. The TV emulator was operating under devicePixelRatio = 1 and we could reproduce it on a Flame with devicePixelRatio force-set to 1. This doesn't seem to be a recent regression as it can be reproducible with at least as early as 2.1. Note that on Flame or a smart-phone set-up, this bug is much less evident -- where the thin line appears as a solid black line which looks too similar to candidate panel and not as distracting as what we're seeing with TV. Also this bug shows iff we display candidate panel with keyboard (thus this is a bug on Keyboard App and not System App's input management/window management).

Hi Rex, John, I'll take a look, but I want to do some testing on DPPX=1 device, but I don't have a buri around. Will try to get a buri and follow up. Thanks for the heads-up.

Heard from John Lu that we could somehow change the DPPX to 1 on Flame. John (Hu), if possible, could you please share with us how to do that? Thanks.

Rudy, Please use uitest to tap a text box which triggers suggestion bar. There is a silver line between suggestion bar and keyboard. According to John Lu, this silver line should be top of suggestion bar instead of bottom of it.

Sorry that I probably won't have time to work on this in the near future. Deassign myself first.

Firefox OS is not being worked on