The shifts within IE's editions may have been partly due to Microsoft's new philosophy of . Late last year, the company said it would begin silently forcing Windows to upgrade IE to the newest-possible edition, ending its earlier practice of asking users' permission before making such a move.

Internet Explorer has been on a multiple-month rebound after hitting an all-time low last December. (Data: Net Applications.)

Beginning in January 2012, Microsoft started upgrading some PCs running Windows XP from IE6 or IE7 to IE8, and swapping IE9 for IE7 or IE8 on Vista and Windows 7.

That new practice would not explain the April increase in IE7, however.

Chrome was the only browser besides IE to post positive numbers for the month, growing by three-tenths of a percentage point to 18.9%. Mozilla's Firefox and Apple's Safari both lost share -- four-tenths and three-tenths of a point, respectively -- to end April at 20.2% and 4.8%.