[imp] 6.1.3 crtl + - resize loses sidebar in Firefox

[Rick Romero]

I didn't see this as a fixed item in the last update, but in Firefox 23.0.1
when I hit CTRL + , the font sizes increase and everything is good.  If I
hit CTRL -, at any time and change the font size to less than the original
font size, both the folder scroll bar and message list scroll bar
disappear.

This also occurs in Chrome 29.0.1547.66 m

Rick