Created attachment 8784401 [details] html file to open in firefox. User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:48.0) Gecko/20100101 Firefox/48.0 Build ID: 20160817112116 Steps to reproduce: Type a text in a input field and put the cursor in the text. Go to the next field with tabulation. A tabulation CharCode(10) is inserted in the text. In the code of the page, there is a listener on keypress for keyCode 9 (TAB) and an alert() function in the listener. preventDefault() on event doesn't modify the behaviour. See attachement for the html file. Actual results: A tabulation is inserted in the text (input field) in addition to the navigation by tab key. Expected results: Only the navigation by tab key to the next field.
Created attachment 8784733 [details] testtab.html Open the file in firefox and follow the instructions: Enter text in the first or second input field and put the cursor inside the text. Then go to the next field with tab key. A tab will be inserted/added in the text.
Almost same bug as bug 1294536. I confirmed it's fixed in the try build there. could be just a dupe?
I think that for easier to find a bug which users to see, keep open this bug and close this bug when bug 1294536 is fixed.
I cannot reproduced with the latest Nightly build. Must be fixed by the fix of bug 1294536.