There is. Use the rectangular Marquee tool to select a section of the image. Copy the section. Choose Edit > Deselect, and then switch back to the regular pointer tool. Choose Edit > Paste to drop the copied section over the original image. With the pasted section selected, choose Blur > Gaussian blur from either the main toolbar or the FW live filters. Draw a white rectangle over the blurred image section. In the layers panel, select the blurred image section and cut it to the clipboard. (Edit > Cut). Click on the white rectangle to select it and Choose Edit > Paste Inside to paste the blurred image section into the rectangle.