Double-clicking a word or click and drag to select is removed by Firefox in Gmail on the first attempt. Subsequent attempts are successful. Action: Open email in Gmail tab in Firefox. Double-click or click and drag a selection. Result: Selection is highlighted for a couple seconds and then is unhighlighted (deselected). Cannot copy the original selection. Expected result: Selection remains highlighted and can be copied by keyboard command or right-click context menu "Copy". Attempted correction: A second attempt to highlight is successful as normal. Selection remains highlighted and available for copy function. This is ONLY in Firefox. Chrome acts as expected first time, every time.