Change the dynamic rubber band display of features being digitized in QGIS

While digitizing new polygon features in QGIS, I found that the dynamic display of the new polygon to obscure other map layers that could aid in the digitizing work. As an example, see the screenshot below: the polygon being digitized is displayed in (almost) opaque red color fill that the features below is almost obscured.

There is a setting in QGIS that controls the color and opacity of the dynamic digitizing display.

To change the dynamic display properties do the following.

1. Select Settings | Options in the application's menu.
   
   The Options | Digitizing dialog box appears.
   
   
2. In the Rubber band field, click on the highlighted area (shown in red circle below).
   
   Note: There is a problem in QGIS 2.2.0 with showing the rubberband color - none is displayed, as shown in the highlighted area of the screen shot above.
   
   The Select Color dialog box appears.
   
   
3. Optional. Choose another color, e.g. purple.
   
4. In the Alpha channel field, type in another value e.g. 80. Click OK.
   
   Note: type in 255 for a fully opaque rubber band and 0 for a fully transparent rubber band.
   
5. Click OK to close the Options | Digitizing dialog box.
   
6. To see the effect, start to digitize another polygon.