Build Identifier: http://hg.mozilla.org/mozilla-central/rev/d37d4edce6dd Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1 ID:20120510145529 xul menulist scroll amount is very little with mouse wheel if mouse pointer move at the same time when general.smoothScroll = true. This is similar to Bug 754196 but that is html element and regression range is also different. Maybe this is same cause of Bug 590082. Reproducible: Always Steps to Reproduce: 1. Set general.smoothScroll to true 2. Open Content Options (Tools > Options > Content OR Edit > Preferences > Content) 3. Open drop down list of "Default font" 4. Try to scroll the list with mouse wheel and move mouse pointer at the same time Actual Results: scroll amount is very little Expected Results: should scroll as usually Regression window(m-c) Works: http://hg.mozilla.org/mozilla-central/rev/b94cf8147ccd Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111140136 Fails: http://hg.mozilla.org/mozilla-central/rev/47cd92d616d7 Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111150802 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b94cf8147ccd&tochange=47cd92d616d7

20160502172042 Mozilla/5.0 (Windows NT 6.1; rv:46.0) Gecko/20100101 Firefox/46.0 20160605030215 Mozilla/5.0 (Windows NT 6.1; rv:49.0) Gecko/20100101 Firefox/49.0 I have tested your issue on latest FF release 46.0.1 and latest Nightly build and could not reproduce it. Is this still reproducible on your end ? If yes, can you please retest this using latest FF release and latest Nightly build (https://nightly.mozilla.org/) and report back the results ? When doing this, please use a new clean Firefox profile, maybe even safe mode, to eliminate custom settings as a possible cause (https://goo.gl/PNe90E).

No