Reproducible on: Aurora 37.0a2 (2015-01-15) and below. Affected platform(s): Ubuntu 14.04 LTS 64-bit, Windows 8.1 64-bit, Mac OS X 10.9.5. Steps to reproduce: 1. Launch Firefox. 2. Enable Responsive Design from the "Developer Tools" → "Responsive Design View" menu. 3. Open the Browser Console from the "Developer Tools" → "Browser Console" menu. 4. Using the Location Bar, go to about:preferences. Expected result: There are no errors displayed for this action and about:preferences is loaded successfully and displayed in responsive mode. Actual result: - about:preferences is loaded with General section selected automatically, but it displays the data from the Search section instead. - content.js:146:8 throws the following error in the Browser Console: > TypeError: preference.setElementValue is not a function - Starting with Firefox 35.0 (20150108202552) and below, the line that throws the error varies a bit: > TypeError: preference.setElementValue is not a function content.js:118 Regression range (m-c): - Last good revision: 770de5942471 (2013-11-05) - First bad revision: 9ba3faa35c96 (2013-11-06) - Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=770de5942471&tochange=9ba3faa35c96 Additional notes: - On Nightly 38.0a1 (2015-01-15) this error message is no longer displayed and is replaced by: > unsafe CPOW usage is thrown TabState.jsm:96:0 - This issue is reproducible with and without e10s enabled.
The new RDM UI shipping in Firefox 52 exits RDM when going to parent process pages like this, so there is no chance for this error to happen anymore.