Easy, you use the new Polaroid Frame plugin.
Polaroid Frame was really just an excuse to play with some of CodeLabs new UI controls (I just love the new Double Vector control) 8) The theory behind this plugin is that the frame and image are always a specific ratio of height vs. width. This is explained in my post here:http://forums.getpai...post__p__203897. This is why you only need one size control, because everything is linked to that size by a set ratio.
The other controls are fairly self explanatory, except for maybe the checkboxes:
Use Primary - Uses the primary color for the frame. Default is the secondary color.
Develop Image - When checked, any underlying image will be shown in the frame. Unchecking this box will fill the image area with a brown color, like an undeveloped polaroid!