User Agent: Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release) Build ID: 20140326030203 Steps to reproduce: On WinXP, with resolution 1024x768 open new tab. Actual results: about:newtab shows 3 cols x 2 rows After pressing ctrl + minus, about:newtab shows 3 cols x 3 rows After pressing the next ctrl + minus, about:newtab shows only 2 cols x 3 rows Expected results: about:newtab should show the number of cols and rows, which is set in about:config, default 3x3 When you don't want to show the specified number of rows if the window can't fit it (bug 980014), Firefox should remember that I have shrunk that page.