<!DOCTYPE html> <html> <head> <title>Stretchy mfenced</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> </head> <body> <!-- See bug 687807 --> <math > <mfenced> <munderover> <mo stretchy="true">→</mo> <mtext>AAAAAA</mtext> <mtext>BBBBBB</mtext> </munderover> </mfenced> </math> </body> </html>