make codemirror horiz split editing work on safari by working around a **BUG**
make codemirror horiz split editing work on safari by working around a **BUG**

tscholl2/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,tscholl2/smc,sagemathinc/smc,DrXyzzy/smc,tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,sagemathinc/smc,sagemathinc/smc