STR: * have a debug profile from gaia * launch firefox nightly with this debug profile * launch the "messages" app * try to inspect elements Expected: * the elements pointed by the mouse are inspected and the "inspecting border" is correctly layed out around the element Actual: * the "inspecting border" is translated by a few pixels to the top Debugging with Paul we saw the bug is not happening when launching the app directly (using http://sms.gaiamobile.org:8080) so it's related to using iframes. However, "normal" iframes on other website do not trigger this bug. This is also not related to the responsive mode, the bug appears when I disable it. Note that this works correctly in Firebug. see screenshots

Just verified that this happens in all other apps I tried too, so this is definitely not related to sms. This also happens in homescreen (which is not the system app), so you don't need to launch the sms app.

I think the offset we're seeing is the size of the status bar on top.

I think it's related to the fact we can't cross <iframe mozbrowser> boundaries. So we think we are in the top level window when we're not.

I figured it out. Patch coming.

This is a symptom of bug 897960.