>>> My Info: Win7_64, Nightly 49, 32bit, ID 20160526082509 STR_1: 1. Open http://www.rp-online.de/ , open any article listed there in a new tab 2. Right-click on the text, then immediately hold left mouse button to start selecting text 3. When context menu appears, hover mouse over option "Select All" and release left mouse button 4. Move mouse over the text AR: text selection continues: it wasn't canceled in Step 3 ER: Either X or Y X) Text selection should be canceled when user releases left mouse button over context menu Y) Context menu should not appear, because user already started text selection, which assumes that 'click' happened outside of context menu after right-click.
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0 Firefox 50.1.0, Build ID: 20161208153507 I have managed to reproduce this issue on the latest Firefox (50.1.0) release and latest Nightly (53.0a1) build.
Too late for firefox 52, mass-wontfix.