FM9: Limited Size of Structure View Panel?

Hi,

I'm using FM 9 on a workstation with two 22" monitors that are rotated 90 deg (portrait orientation). When I try to resize the structure view panel to fill the right monitor (as I could with FM7.2 and FM8) I can drag it to only about 40% of the screen.

Furthermore, there seems to be no way to fully expand this as with FM7.2 and FM8.

Is there any way to further resize the structure panel?

Thanks,

Matt

EDIT: I'm using FMV9 V255