Resizing a window in GNOME-2 has always been a difficult task. Hundreds of other GNOME users agree (as can be seen from the following reports: http://brainstorm.ubuntu.com/item/2571/). 

Unfortunately, the latest Beta release of GNOME-shell still makes resizing a window a major undertaking. The user first tries in vain to get the resize-cursor to appear. Then (after much effort) the resize-cursor fails to "latch on" and the mouse movement causes the cursor to change again before a resize is accomplished. It is an effort in futility just to resize a window. Most users resort to using Alt + Middle-click. But this requires two hands and isn't always practical. Plus, it is difficult if not impossible to do on laptops.

My hope is that this post will generate the needed attention to fix this issue before the release of GNOME-Shell. I am open to however GNOME wants to fix it. In the provided link numerous suggestions are offered. I would suggest simply to create a visual marker on the window border where resizing can be easily accomplished with little effort.